This idea doesn't want to leave my head and I don't have enough time to spare it on this, so I'm posting this here.
So, I really hate the idea that you can't persuade Balgruuf into joining the Stormcloaks - he himself is obviously torn between two factions. But I understand his initial idea to ally himself with Tullius to protect his citizens from the Dominium.
BUT. Balgruuf is a very honourable man, eager to duel with Ulfric to the death, even if this would meant his death. And here comes my idea:
Dragonborn challenges Balgruuf in the name of Ulfric and his rebellion.
As a challenge made publicly, Balgruuf wouldn't be able to say "no" and I doubt he would try to do it anyway. He's already afraid that using the Imperials might be a cowardice. He accepts, reluctuntly and expressing his disappointment.
He goes to change himself into armour (to keep immersion). You go into that wide area in front of the main doors while the rest stays on the stairs, watching. There might be a short talk with Balgruuf, when he states that he doesn't care what you use since he will also use all his skills (players who like to roleplay will be able to have some... roleplaying here).
Balgruuf defeated. He knees (wounded/tired/etc. pose) and you can do two things - kill him or spare him. There are no problems with Balgruuf getting killed since he was supposed to die in Mephala quest and all necessary scripts and recordings for Hrongar are still in the game.
Player defeated. The world blackouts as your character is knocked to the ground. Balgruuf spares you and you wake up outside the gates with a soldier informing you that the Jarl was merciful. And you return to Ulfric with the axe and conquer Whiterun, etc. (though it would be a good idea to get rid of that "disappointment" talk from Balgruuf to keep immersion).
Victory. Balgruuf or Hrongar promise support, Whiterun is in the hands of Stormcloaks. Since Tullius was not informed by neither player or Balgruuf about the Stormcloaks plans, there is no battle - when he gets the news, it is already too late.
It would be also good to add some unique dialogues for Balgruuf, Hrongar, Galmar and Ulfric after defeating the Jarl. And killing him.
That's my whole idea. Like it or not, I'm glad to have it out of my head. Now, I can do something useful.
PS: I don't think there is something like this out there - if there is, I'm sorry, I didn't notice that before.
Edited by nayakri, 18 October 2018 - 12:47 PM.