Based on the trailer, it seems that the division of the Avengers will not come as an offshoot of the new legislation to put a leash on the superheroes but because of Steve Rogers’ friendship with Bucky Barnes.
Steve is the alter ego of Captain America while Bucky is the alter ego of the Winter Soldier. It seems that Cap believes that he could change the Winter Soldier because he is still Bucky inside and he seems to have started succeeding on it when the Winter Soldier said that he remembers Steve’s mother and his newspaper shoes.
Amid the progress made by Cap on the Winter Soldier, people and some other Avengers are upset about the things that he did during “Captain America: The Winter Soldier,” and wants him to pay for his actions.
Because Captain America is playing on his relationship with Bucky, General Ross spoke to him and said that the star-spangled superhero is actually a vigilante.
Ross said that superheroes operating with unlimited power and no supervision are something that the world can no longer tolerate.
And that is where the main plotline of “Captain America: Civil War” shall revolve. Interestingly the trailer also showed Captain America and the Winter Soldier working together and battling Iron Man in the trailer, which only indicate that the friendship of Steve and Bucky really came to play.