Straight off the bat, in the Sims 4, I made a Babar themed save file, I gave Cornelius the last name 'Olde', in reference that he's from the Old kingdom.
Damian is on the right, and Cornelius is on the left.
Cornelius has the scar on his nose, because it was a result from an injury when he was a child, not from fighting gangs, or pirates. Just clumsy, bad luck, doesn't help that he's legally blind. (At least I headcanon that he's legally blind, because of the episode, 'helping hands', I feel like that man must've had a strong prescription)

Damian's little origin story: I gave Cornelius a twin brother because when he was born in the Sims 4, he randomly got a twin, and I decided to keep him. He became a high maintenance, Ambitious, and annoying MF. (the bad part of randomizing traits in the sims 4, but I didn't want the twins to have the same traits either, I'm just happy that he didn't become an evil twin)
Cornelius also got twin younger sisters, in the Sims 4, who are named and no joke, Annabelle, and Isabelle. This happened when I was playing with a different family, I showed up to the house, and there were the girls. I cheated to rename the girls Annabella, and Isabella.