Vegeta takes the role of Asriel from Undertale
Vegeta is the biological son of King Vegeta and Rosicheena, also the adoptive brother of Blakku (first fallen human). He appears ONLY in the True Pacifist route as the Prince of Hyperdeath.
As his child, his appearence looks like King Vegeta's, but only with a pair of scruffy bangs.
In Hyperdeath form, he looks exactly like his father, but without a beard. And he has markings on his cheeks, with black eyes and white pupils.