Otto von Bismarck has been easily the dominant figure at the negotiations, dictating terms with little resistance from other parties. He attempted to follow his usual foreign policy of cozying up to both Austria and Russia in order to create a super-alliance that would dominate Europe. However, that did not work out because in order to appease Austria, Bismarck had to significantly reduce Russia's gains in the Russo-Turkish war as per the Treaty of Berlin, which resulted in the cooling of Russian-German relations (and the subsequent formation of the Triple Entente).
In this alternate timeline, Otto von Bismarck had a moment of epiphany and realised he cannot appease both Austria and Russia at the treaty of Berlin and chose to focus on appeasing Russia, thus letting Bulgaria keep most of the gains from the Treaty of San Stefano, with only token concessions to the Ottoman Empire in order to avoid immediate hostility from Britain and France.
The result of this would be significantly closer relations between Germany and Russia than in OTL at the cost of hostility between Germany and Austria. In order to secure Russia's interest in staying in the alliance and to make it more useful as an ally, Germany would likely mirror OTL's France/Britain and would heavily invest into the Russian economy. Similarly, Italy would be much more interested in backing Germany in major wars if Germany was hostile to Austria because of Italian claims on Trentino, Istria, and Dalmatia. All of this would result in a very solid Germany-Russia-Italy alliance.
A Germany-Russia-Italy alliance would have several downstream effects. First of all, Austria, surrounded by enemies on all sides, would desperately seek any alliance it can find, with the obvious contenders being Britain and France, neither having great relations with Germany or Russia. Second, the Ottoman Empire would similarly seek protection.
Thus, the web of alliances is Germany-Russia-Italy-Bulgaria against Britain-France-Austria-Ottomans. However, I believe this would be less volatile than OTL. In OTL, the Great War broke out because all sides felt confident in their strength. In this timeline, a German-Russian alliance would likely be seen as an unstoppable juggernaut in a land war, changing everyone else's strategy to containment by non-war means and avoiding major wars at all costs (unless it was forced by an attempt to partition Austria or something similar). However, if the Great War did break out, I believe the German-Russian-Italian-Bulgarian alliance would win with ease - after all, Russia was much stronger in every respect than Austria and the Ottomans combined, and one of the main reasons Germany lost the Great War in OTL in any case was the blockade which prevented them from importing food and other resources - something Russia has plenty of, rendering the blockade meaningless.
This overwhelming advantage on their side would make a communist revolution in Russia far less likely. Moreover, in OTL, one of the major factors in the communist revolution was Germany sending three trains full of revolutionaries (including Lenin himself), gold, and pre-printed propaganda to Russia, which is something that just wouldn't happen in this timeline, meaning the Soviet Union would never happen.
The result of this all would be a much different world from today.
In this alternate timeline, Otto von Bismarck had a moment of epiphany and realised he cannot appease both Austria and Russia at the treaty of Berlin and chose to focus on appeasing Russia, thus letting Bulgaria keep most of the gains from the Treaty of San Stefano, with only token concessions to the Ottoman Empire in order to avoid immediate hostility from Britain and France.
The result of this would be significantly closer relations between Germany and Russia than in OTL at the cost of hostility between Germany and Austria. In order to secure Russia's interest in staying in the alliance and to make it more useful as an ally, Germany would likely mirror OTL's France/Britain and would heavily invest into the Russian economy. Similarly, Italy would be much more interested in backing Germany in major wars if Germany was hostile to Austria because of Italian claims on Trentino, Istria, and Dalmatia. All of this would result in a very solid Germany-Russia-Italy alliance.
A Germany-Russia-Italy alliance would have several downstream effects. First of all, Austria, surrounded by enemies on all sides, would desperately seek any alliance it can find, with the obvious contenders being Britain and France, neither having great relations with Germany or Russia. Second, the Ottoman Empire would similarly seek protection.
Thus, the web of alliances is Germany-Russia-Italy-Bulgaria against Britain-France-Austria-Ottomans. However, I believe this would be less volatile than OTL. In OTL, the Great War broke out because all sides felt confident in their strength. In this timeline, a German-Russian alliance would likely be seen as an unstoppable juggernaut in a land war, changing everyone else's strategy to containment by non-war means and avoiding major wars at all costs (unless it was forced by an attempt to partition Austria or something similar). However, if the Great War did break out, I believe the German-Russian-Italian-Bulgarian alliance would win with ease - after all, Russia was much stronger in every respect than Austria and the Ottomans combined, and one of the main reasons Germany lost the Great War in OTL in any case was the blockade which prevented them from importing food and other resources - something Russia has plenty of, rendering the blockade meaningless.
This overwhelming advantage on their side would make a communist revolution in Russia far less likely. Moreover, in OTL, one of the major factors in the communist revolution was Germany sending three trains full of revolutionaries (including Lenin himself), gold, and pre-printed propaganda to Russia, which is something that just wouldn't happen in this timeline, meaning the Soviet Union would never happen.
The result of this all would be a much different world from today.