I feel like it's a bit of a clusterfuck. There seemed to be some disbelief in the aftermath of the OTL battle that things actually got to the point of violence. (And, of course, once it did, there was no going back. The county was already a toxic stew of resentment and politics -- adding blood feuds to the mix made civil war inevitable.)
Yeah, this makes the Wars of the Roses even more chaotic, it’s a child vs a man who has committed a mortal sin. Neither choice is good, it really boils down to a choice of who is the lesser of two evils.
In ATL, the death of king would surely turn those on the sidelines strongly against the emerging Yorkist faction, and the death of the king's favorite would remove the most obvious and immediate problem for the royalists. York may in fact surrender himself to royal custody in some act of chivalry, expecting mercy from wiser councilors now that Somerset is gone
I imagine there would be a good few who defect from York’s army following the Battle and some of his allies may even abandon him, since Warwick was disgusted at how Richard treated Henry VI in captivity in OTL, so imagine his reaction to Richard killing him. Surrendering might not be Richard’s worse choice here, though it depends on how much influence Margaret of Anjou wields in the Regency here.
only to find a vengeful Margaret ready to take his head.
I am imagining Margaret of Anjou, ordering
And if he doesn't, well, there's no chance the king's murderer is going to take control of the regency. This wasn't 1399 -- people didn't hate Henry, they, like the French a half-century prior, just didn't know what the hell to do with a mad king.
Yeah, Henry VI’s death is Richard’s main impediment to taking the throne/regency here, since he has committed a mortal sin and a fairly religious era and most Englishmen hated Henry VI’s advisors not Henry himself.
Well Buckingham was captured in that battle so he will not be the regent and York would surely claim the Crown at this point as the rumors on Westminster’s paternity were already well know AND he has a strong claim on his own.
I had forgotten that Buckingham was captured following the Battle, so that hurts the Lancastrians cause. As for the questions about Westminster’s paternity, I have read they didn’t start until as 1460, when the Act of Accord was brought into effect. Though, Richard of York’s best bet here is to press his claim ASAP, before word of Henry VI’s death spreads across all of England.
No one wants a child king, so we probably have Richard of York take the throne as Richard III.
Edward’s youth is the main obstacle he has to keeping the throne, but it’s worth nothing most of York’s enemies and those who were neutral towards him are likely going to oppose him since he has committed a mortal sin. Plus some of his own men may desert him here (a few soldiers defected in OTL following the Battle of St Alban’s, so imagine how many will defect here when Henry VI is outright killed, especially since he (Henry) originally wanted a diplomatic solution). Then again Richard does have the manpower and money from his own lands here to take the throne. So it’s sort of 50/50 here.
And who will support Yorkist king instead of Henry's sane son? Richard is regent at best
Yeah, Warwick and Salisbury will support Richard, since it’s their best chance at saving their skin, however Richard’s supporters from OTL may not join him here since he has just destroyed the popularity he had.
Warwick, and I am sure a lot of others. Edward of Lancaster is practically a baby, so no one knows if he is sane.
I am not sure “a lot of others” would join Richard here. At this point his entire goal was to remove the King’s evil counsellors from power, but here has killed said evil counsellors and the King, which is way too far for many. Plus many religious people will oppose him since he has committed a mortal sin of killing a King. Also Warwick was reportedly disgusted at how Richard treated Henry as a prisoner, so I can only imagine his reaction to Richard’s men killing the King, so he may defect in a bid to get a pardon here. Again it could go either way as to who gets the throne in this scenario,
And yet, York has the dishonour of having become a traitor and a King Killer.
Yeah, this is going to be the biggest problem towards Richard getting the throne + his reign assuming he gets the throne here.