So, I think I have a theory for the Marionette. In FNaF2, in the death minigame, you play as the marionette giving the dead children presents and then give them the suits. I think that the purple guy killed the children, which has obviously been confirmed, but the marionette is the one that kind of tried to save them by giving them the suits even if that means they are confined in the suits forever. I don't think that he has any control over them, but is also another child that has been killed as some people think that more than 5 children were killed.
In FNaF3, in one of the secret minigames in which Markiplier shows, there is actually a child in gray at a party with a puppet mask on. Whether the fact that he is already gray, may mean that he is already dead, but he still gives cake and his soul is free. I think that the Marionette was a child which was killed, maybe at an earlier time I don't know, but I don't think he controls the other animatronics like some people think. This is just my opinion and I am open to any suggestions against or for this theory (even though there isnt really a theory there)