It was in the Brit comics where he discovered that he was a robot after going through a helicopter crash. He also had a family but underwent a divorce because his wife couldn’t handle him being cold on the outside. They did eventually came back together after Donald gained more humanity though. Donald has a lot of a bigger role in the Brit comics than Invincible as he had more character development over there.
Well Nolan was more brutal such as the train scene and the time gap between the reveal and thraxa is much compared to the comics.