Thank you for the reply, I shall do my best to address your concerns and questions.
As far as the coup goes, Himmler was acting on the behalf of Hess in order to suppress a Wehrmacht coup, which did in fact happen. Hess is not a very well respected man as a Führer, he was a sycophant who lacked the ambition and drive for leadership the others had, he only desired to follow Hitler and do his bidding. In fact, the Party Salute continued to salute Hitler rather than Hess, the oaths of loyalty were given to Hitler and Hess did not renew those before the coup attempt, which is one of the excuses the Wehr plotters used to convince more reluctant conspirators. Hess does have the power to replace Heydrich, however he lacks the decisiveness to do so while Reinhard has material to blackmail him, and from the way the coup was launched, Heydrich did show himself loyal to him by defusing Himmler's conspiracy. Himmler originally planned to do launch a preemptive coup after the RSHA discovered the plot for that day, and use the chaos in order to eliminate enemies of his own. He made two main mistakes: He left Bormann alive and trusted Heydrich with the task to neutralize Goebbels. Bormann was supposed to have died that day in order for the "Loyal Heinrich" to take the place of Deputy, but the coup was launched too soon, before the Wehrmacht made it's move, and to have him die would be either a show that the SS could not protect the Second man in the Party, or reveal their complicity. There were many SS officers who were unsatisfied with Hess, during his short tenure as a Führer he had publicly shown himself as a weak and vacillating man who pulled out from the war preparations that Hitler ordered and wanted a Detente with Britain, even backing down during the Dakkar crisis. It goes into the core of the Social Darwinianism of the National Socialist ideology, the leader is supposed to be the incarnation of the Nation to which all obey, and a weak leader would necessarily lead to a weaker nation. Publicly they could not oppose Hess, but that doesn't mean they wouldn't secretly plot to bring a more worthy man in charge.
Heydrich would certainly not be opposed to being Deputy Führer for the simple fact that position is made far more powerful after Hitler's death. Officially the Deputy was never supposed to be a successor, but as Hitler's Will established the precedence of the "throne" passing on to the Deputy-Führer, it is a position many loyal hitlerites would adopt within the Party. Hess and others will attempt to limit the power Heydrich has in the office, but Heydrich already used the coup as an excuse to unleash a purge, the Second Night of the Long Knives. Sure, it was mostly targeted at Wehr officers, former Weimar politicians, and associates of the Schwarze Kapelle, but he did make sure that some of Bormann's loyalists, ended up on the list on the following days. With Europe seeing a surge in rebellious activities, it was not hard to disguise the deaths of certain Gauleiters or party officers as resistance attacks or plane crashes, such as what is implied to have happened with Göring. He is still far from solidified in his newfound power, and will need allies in order to stay afloat, or end up on a ditch like so many others.
The Police is still under the command of Heydrich as he was given Himmler's former offices, although the Ministry of the Interior was given to Inquart. The Majority of the Police forces and powers, including the Gestapo, have been integrated as part of the RSHA as the Cold War would force the Reich to centralize it's security apparatus to deal with the MI6, OSS, and Mossad which will constantly seek to destabilize the newly conquered European Empire.
Adolf Wagner was a figure I was thinking of including in the Hess Führership due to his ideas, however I had to cast him aside after seeing the Chronic Alcoholism and his deteriorating health even back in the early 40s. Geisler took his offices and now leads the SA after his death. As for Speer, I plan to go over the details in a future chapter about the three members of the "Triumvirate" (Heydrich, Goebbels and Speer), who are the main obstacles to any plans Hess may have for Partification. While Bormann certainly would've been a bigger threat if alive, Hess is a man who has the power, but lacks much of the will to use it other than continuing Hitler's memory, you could almost stretch it in calling the Reich under Hess as a Necrocracy, a nation ruled by a dead man. Am I making Hess excessively submissive? Perhaps that is a matter one could discuss as to what extent he had a will of his own or he was just blindly following Hitler's desires with a sense of Naivety? After all he is the man who did fly to Britain in one of the most bizzare events in WWII. The notion I have is that Hess was a man Hitler put in the position he was because he would never pose a threat to him, and a Hess that stays in his position for another decade where Hitler just managed to seem like a Messiah to him, would be even more dependent. At that point, Hess would be more of a spokesman, a hype man for Hitler that was kept around because he was a loyal old friend from the early days, with Bormann usually taking up his duties, what would Hess do after both Bormann and Hitler are gone? He could either become more assertive, using his power in order to act for the Party's interests and defeat his trio of powerful underlings, or he would slink more and more as a mere shadow of Hitler, acting as if he was still a deputy to a man he spent 30 years being nothing but fanatically loyal towards.
Comes in the question of Morell. I myself had some hesitation on Hitler's death and what would be publicly announced. There weren't many options, the NSDAP in it's propaganda always showed Hitler as a strong and healthy leader, delivering powerful speeches and seemingly being invulnerable as he defeated every foe in his way. He was still 61 by the time he died, which was below the usual expectations of a man that always had a carefully crafted image. IOTL, the propaganda films always did their best to hide Hitler's frail state, and the same would happen in here. Saying that he died of something as simple as a flu would be a disaster to that image, as he was still relatively young and just recently had made public apperances in Germania. The alternative was to say he was killed by a foreign agent, but not only that also would be terrible PR for the Security agencies, that would make the war essentially inevitable. Very few in the leadership truly wanted to start a war, Speer knew that the Reich did not possess the nuclear capacity to challenge the US, and a hundred german cities would be destroyed before even a single nuke could be deployed. The SS, despite their outward fanaticism, still was led by Himmler, the same man who was desperately trying to jump the boat in 1945 and would not want to risk that Speer's theories are true when he had a chance of ruling an intact Europe. Bormann had a similar line of thought, his efforts were mostly directed towards the internal fighting for the Party's control. Heydrich knew from the RSHA that the United States was a far more formidable opponent than Hitler would admit, and Speer's thoughts that at least a nuclear parity had to be reached before any conflict made sense. There are only so many options you can use without making Hitler look weak (After all their whole legitimacy to power came from him and the image created of him) or incompetent (It doesn't fit well to say the truth that Hitler was a hipocondriac who overdosed himself). Yes, Morell makes things tricky for them and is not the most pleasant scapegoat, but in the limited array of options they had, it was less of a damage to take a temporary hit than to let the carefully crafted image of Hitler be hit, something a man like Goebbels would know. Besides, they all hated Morell and considered him a charlatan so that was a convenient way to get revenge on him.
Any further questions?
Thanks for the answers. Well, I have to admit I was a bit confused about the coup.
The Coup
So the coup developed as this: the SD (the Abwehr would have probably been integrated in it, it had happened in 1944 IOTL and ITTL Himmler and Schellenberg would have all the time and prestige necessary to push for this after the war if they hadn't managed to do it before) gets wind of unusual army manoeuvres; since the SD is closely controlled by Himmler and perhaps the prevailing mood in it is that Hess is at least ineffectual as leader, the information isn't relaid to Hess. So when the coup is launched, Himmler is able to appear to act according to the law: the Reichssichercheitdienst (RSD), the agency responsible for the protection of government and Party leaders and important figures could sequester ministers at their homes or offices and transfer Bormann and Hess to an isolated location "for maximum security". Himmler can then manage to take over, by preparing to purge any opponents after these events by claiming that they were implicated at the coup attempt.
However this is spoiled when Heydrich turns on him, realising perhaps the potential to be the power brker at that moment and extract concessions from all parties, if necessary. So he leaves Goebbels unscathed and turns on Himmler, bringing the coup to an end. They still have some loose ends, like the death of Bormann (it is difficult to say that the army units in revolt broke in the RSHA and managed to get their hands on him), but in general, they could perhaps create a good enough story.
I hope I got this right
So, Heydrich is appointed Deputy Führer. Unless Hess reorganised the office and made it more like its OTL successor, the Party Chancellery, I think Heydrich would prefer nominating a loyal Party member for the post while he would remain on the sidelines. The reasons I am saying this are that:
a) the original duties of the office included a whole lot of public occasions that the holder had to attend, something Heydrich wouldn't like at all (his character and even his pitched voice for example would be an issue). Since Bormann was his predecessor, perhaps Hess has indeed made the office more bureaucratic/administrative in nature, which would solve these issues.
b) the more important reason to consider, it would basically allow Heydrich to take over the Party machinery, since Bormann and Hess had long centralised power in the StdF. I am not sure either that Hess would concede to this or that Heydrich's negotiating position would be that strong thathe could get such a high price.
By that I mean that it would be rather difficult for Hess to find himself in a position like the one he was ITTL. In our world, when Valkyrie was implemented, the coup had begun to unravel long before Remer arrived to the Reserve Army Headquarters and court-martialled the officers involved; when he went to arrest Goebbels, he didn't arrest him immediately, due to the situation being without precedent. When Hitler talked to Remer and ordered him to arrest the officers who instigated this, he didn't question this; it wasn't
just the power of Hitler, but, more boringly, the fact that he was the highest authority in the army, as its Commander in Chief, his orders were to be obeyed without question (the Wehrmacht had a very clear line of command, and its officers were drilled hard in the idea to obey the orders of the superiors). From the story thus far, at least by my understanding (so sorry if I've got this wrong again), the Oberkommando der Wehrmacht (OKW) hasn't been involved. So this means that Keitel is out of the loop on this one; he would get calls from officers of the mobilised units who would just want to be sure that what they were doing was legal. If he were to tell them that no, there is no reason for them to be mobilised, they would follow his orders, since he would be, as chief of the OKW, the second highest ranking officer in the hierarchy.
Also, about Hess and Bormann, if Hess ordered his RSD guards to leave Bormann with him, I don't think that they would disobey the order, not even if the counterargument that they were to be separated for Hess' own protection was brought up (which would be weak, since if they suspected Bormann, they wouldn't have isolated him in an ordinary room, since he could in theory attempt to commit suicide while the RSHA would need him alive for questioning); and Hess would probably be shaken enought that he would want people he believed he could trust. So, unless you throw Hess in a fit of paranoia, he and Bormann would be in the same room. There, after Bormann had recovered from his initial shock, he would gather his wits and see the situation, telling Hess to contact the OKW immediately to have the rest of the army mobilised. The RSD could hardly refuse such a request, and I doubt that they could claim that all their telephone connections would have been severed. Once Hess, or Bormann, had been on the phone and reached the OKW, it would basically be game over for the conspirators. So, by the time Heydrich would arrive, it would be rather late for him to bargain for anything.
For the opposite to happen, I think it would take two more things: one, that the OKW would have been brought in the conspiracy, and two, that Hess would be incapacitated. Now the second one happen perhaps if Hess has a breakdown and is resigned. Had this happened, he would probably say nothing when the RSD men isolated him and remain passive for the duration of the coup, but would be difficult. The first one would largely (but not entirely) depend on the aforementioned development: if Hess had been out of reach and the OKW was with the coup officers, then a larger number of army units would probably side with the coup, since the OKW could spin it as the SS pulling a coup. However, if the OKW staff had been brought in the plan and Himmler was aware of this, he would have probably broken the news to Hess, simply because the brewing army coup would have been more dangerous for him and his plans than a small delay and the subsequent purge would allow him to weaken army opposition, strengthen the position of the Waffen SS in it and gain more Hess' trsut, therefore having an easier time pulling his coup another time (Himmler wasn't driven by conviction alone, he was a very competent infighter too, which is largely what helped him build his empire). Without the OKW on board, its leadership, if only out of fear of backing the wrong player, would at least order the units to stand down or assume direct control from the officers until the situation was clear, and the officers would have little option but to follow these orders; and without Hess neutralised, his orders would conuntermand everyone else's, including the OKW's.
Heydrich's promotions
Assuming that these two happened and were effective, and the story progressed as it currently is, there would be questions after the coup: first of all, why didn't Heydrich, who would be the one who would have received the information first - hand, gone to the Führer personally to present him the evidence. Perhaps he could say that Bormann was implicated as well, and with him most likely controlling the whole investigation process (as he would control both the Gestapo and the other agencies that would be involved in it), it would have a chance of standing. Perhaps Heydrich could then lead Hess to conduct a new purge of the Party, which he could direct against his potential enemies, thus eliminating most of the opposition to his appointment as Deputy Führer. However, again, it would be a tough story to sell, since if he was so sure, he could still have informed the Führer, by other means, while Bormann's proteges wouldn't stay idle, for their future would be at stake too; it would be difficult for Hess I think to act with utter ruthlessness and very quickly in this case, since we are talking about people he had been working with for 20 or 30 years and people who had been in the same faction with him, the Control Faction, so people in Bormann's staff would have at least numerous chances to try to convince Hess. Therefore it's not so certain that whether Heydrich would manage to pull this off.
Heydrich's position and the succession question
About the succession thing: Hitler's will was still a will. At least by my understanding, Hitler's will would be binding only at the time of its execution: by that I mean that the fact that Hitler would have nominated Hess (I think another important thing is that he named
Hess, not the
Deputy Führer as an office) doesn't mean that Hess has to do the same. The will was about Hitler, and while he and his office would be identified, the legal differences would be there. Personally I think that in general, there would have been attempts to address the matter of the succession in a more official way: the Party at least would want to ensure that their fortunes wouldn't be subject to the whims of each Führer, since a precedent wouldn't be binding, and that they would always be a seat on the table for them. Enter the Constitution.
A major problem in German political and legal circles was that the creation of the National Socialist state was a gradual and often not completed process: the power of the Führer and the Party rested on special dispensations and emergency measures (the Enabling Act), legislative measures (the Law about the unity of Party and State) and Führer decrees (which increasingly formed the bulk of legislation as time passed). But in effect, all these resulted, technically, from the old Weimar constitution; therefore, it was expected that at some point, a new constitution would be needed, one to reflect the character and situation of the new, National Socialist state. There had been various proposals for constitutional reform, starting from 1935 iirc; while the war postponed these discussions to a large extent, after the war, they would return to the forefront, as the Party would seek to consolidate its position and settle a vast array of issues, from Party - State relations to Reichsreform-related questions, such as the future of the Länder. Succession would also be touched, since I expect that the StdF would be rather anxious about the prospect of Göring taking over; however, Hitler's potential opposition to discussions around this issue and Göring's death would probably put the matter on the backburner, as the immediate danger would seem to be no more and Bormann et co. would turn their attention to other matters.
So it is possible that when Hess comes to power, the succession is open. He would have two options: either follow Hitler's example and make himself the sole arbiter of the issue, deciding the succession in his own will; or decide to establish a formal line of sucession, in turn either dependent on his choice (like the Führer chooses the first option, and if he incapacitated, there is a fomal line of succession) or "fully independent" (like the succession isn't given to persons as persons, but to persons as office holders and is preset). Bormann would reopen the matter and probably push the last option, for it would be the most secure for the Party and would allow him to better influence and control the process, but in front of Hess' potential intrasigence (after all, how is he supposed to be omnipotent when he can't choose his successor), he could try to reach a middle ground, where the Führer has to consult the senior Party officials before nominating the first-order successor. While this wouldn't be "bullet - proof", it would give Bormann the chance to be able to influence Hess' decision and in general steer future Führers in a similar fashion. He could sell it to Hess perhaps as a sort of the "Senate" Hitler had mentioned on various occasions, something that would have the desired effect on Hess.
Of course, succession would be a very sensitive matter, which means that it would probably still be open when the coup would have erupted. The coup itself, with the eventuality of Hess dying with no succession having become more than distant would in turn breathe new life into the discussions on the matter. This time the Party and the Control Faction would be faced with a rather big problem: while before the coup, it would be ideal from their point of view to make the Deputy Führer the successor, now they have Heydrich occupting the office, which instantly derails their plans; worse, with Bormann dead, the Control Faction would be in disarray or at least in serious trouble, as Bormann's enemies inside the Party would try to capitalise on the sudden void to advance their own position and enemies from without would do the same. That would Heydrich time to consolidate his position, but it would be only brief: for what it matters, Hess is still committed to partification and the Party Chancellery staff would probably manage to reorganise. Klopfer, Friedrichs, Hoffmann would all be around and I don't think that Hess would remove them; since he wouldn't trust Heydrich, these three could therefore bypass him and gain direct access to the Führer. Of course Heydrich wouldn't remain inactive, but he would face major difficulties with being from the SS. Hoffmann et co. could perhaps pull all sorts of tricks, like making it mandatory that all StdF personnel being from inside the Party and perhaps having spent a period of time in purely Party positions that would bar most SS personnel. Another way, somewhat complemetary, could be to actually start gradually weakening the position of the Deputy Führer: this would be difficult, for the most obvious way to achieve this would probably be to reverse the previous course and actually devolve responsibilities; perhaps they could avoid this by actually transferring most administrative responsibilities to the one remaining Reichsleiter office that could be considered to be in their favour: the office of the Reichsschatzmeister der NSDAP (Treasury), under Schwartz. It could be easily disguised as an effort to reduce bureaucracy, and since the office dealt with all financial matters, gradually adding more administrative duties would be possible; considering that Hess, if not out of calculation, then out of spite and commitment to the Party/the Control Faction, would probably want to neutralise Heydrich, then it could happen. If this was to succeed, then the Control Faction would most likely manage to turn the StdF into a shadow of its former self.
Still though, this would solve the problem only until Hess' death, or change of mind on the subject and Heydrich would try to counter the moves of the Control Faction; so perhaps the Party people would consider going once again for the independent option: a Senate would elect the next Führer. The Führer could in theory get his candidate by being able to place supporters of his and his supported candidate in that body when necessary and since its members would most likely drawn from the Gauleiter corps, where the majority would probably be people like Lauterbacher, and thus loyal to the central Party line, it would be possible to secure that the Party/Control Faction would control the process. Heydrich would of course attempt to prevent this: he wouldn't be without some cards up his sleeve, for a good number of Gauleiter would have SS titles and feel closer to the SS, and his control of the Police would allow him to use investigation into criminal activities to purge enemy elements and thus be able to promote his own people; but it would make things much more difficult for him.
(I hope my comment doesn't have any factual errors 😅