If I wrote the script (and nobody has asked me yet ) I'd start with him as an intense, sort of creepy child (think Damien). I'd make both his mother and father a little frightened of him, though they would also clearly love him. I'd show the aristocracy as complete bastards who treat the people of Latveria horribly. When his mother dies, I'd make it clear that Doom doesn't have the same sadness and vulnerability that we'd expect from a child, but rather an anger that the aristocracy has 'taken her' from him. I would show him and his father on the run from the aristocracy so that even though Doom isn't a hero, he is a victim of that evil aristocracy. I would make both Doom's father and Boris somewhat sympathetic so that even though Doom wouldn't be a good-guy, some of that sympathy and their love for him would rub off on the audience. In the second act, we'd see the death of Doom's father, and Doom left in the care of Boris. at the beginning of the third act, I'd show an older Doom in college, but I'd only show that briefly. We'd see the accident and then Doom and Boris in the mountains where he would forge his armor with the help of the monks. The final 10 minutes would be Doom in full armor completely and mercilesly destroying the aristocracy and taking his thorne. It would be similar to the scene of Vader in Rogue One, but a little more satisfying in my mind because the Aristocracy would have been shown to be such bastards that the audience would be perversely rooting for Doom to slaughter them. BUT I would only want to do all that after Doom had been introduced and established as the ultimate villain.