Out of everything, I feel compelled to give an answer to this, for some reason. The reason why I came up with this concept was due to the fact that Jericho is Slade Wilson's deceased son in the comics, but never addressed in the animated series at all, thus opening doors to so much possibilities as a story.
Like quite a few people over here mentioned, the gameplay WILL consist of him deciding whether or not to possess more than just his allies, but certain enemies as well. That's why we released a list of characters that we plan to bring into the game, including Rose Wilson.
As for your concern about how you as the player decide to "tear the Titans apart", I won't give too much spoilers to the ending. But I can assure you that there is definitely a plot twist available, so look forward to that
The only thing I was too lazy to write about was how Terra survived her own incident, but I'll leave that to your imaginations LOL.