Mystery of Grisha..possible link to annie, bertholdt, and reiner

[Eragrost]

To start my theory off... the colossal titan appears after grisha says he got some meeting in the inner walls and departs.. the titan invasion then begins we know that the colossal titan and armored titan that break the walls are reiner and bertholdt.. they infiltrate the walls later as recruits in training.. after the invasion.. we see grisha in a scene crying while he injects Eren with the serum to transform into a titan and gives him the key to the mysterious basement that supposedly gots all the answers. Grisha then disappears randomly.. and we hear nothing about him again. He must have some connection with that invasion I think.. he maybe the one who possibly turned annie, bertholdt, and reiner into titans.. and maybe apart of a group outside the walls. Seems maybe grisha had second thoughts bout his role in all this as we can see him clearly crying as he gives his son this power.. maybe regret for some actions of his that maybe linked to this group. The motives of this group so far are not totally clear.. they wanted to destroy the walls.. when finding eren is a titan they suddenly shifted to wanting to capture him.. since we know grisha has had all this knowledge all along and hid it from everyone . His knowledge of the titans.. the serum he injects into eren and the mysterious basement that supposedly has answers to everything going on with the titans or who knows what's down there.. grisha of coarse disappears as I said.. he is maybe in this group or organization outside the walls, why? no answers yet its really unclear.. and why do they want to destroy the walls and possibly mankind inside the walls who knows.. maybe they know something that the people inside the walls don't .. like maybe grisha and that group knows bout for example the titans inside the walls and the whole truth that the wallots or wallets lol are hiding  what or who is this group is still unknown.. but I believe assuming grisha has something to do with this isn't far off.. since so far he's the only one ( besides annie, bertholdt, reiner , and even maybe ymir) whos been revealed to us knowing something bout the titans.. he must know something to be able to turn his son into a titan afterall lol