in an au where vlad wasnt aggressively vengeful toward jack or futilely obsessed with maddie, but instead chose to move on with his life, it’s entirely likely that he never would have held the 20th college reunion and thus never would have met danny
danny never had his archrival, so he progressed at something like a normal rate, eventually finding his teachers in the Far Frozen and learning about things like duplication and his core powers from them. he lives as normal a life as he can, between the fights he has with other ghosts, spending time with tucker and sam, and eventually his college education. sometimes he wonders about the existence of other halfas, but has come to the conclusion that he’s glad nobody else had to go through the pain of his initial transformation.
vlad remained focused on his companies and, to a lesser extent, his own private ghostly research. he performs tests on willing (and occasionally unwilling) ghosts and compares them to the tests he runs on himself, trying to discern the strengths and weaknesses of a halfa. sometimes he wishes for a different test subject, but wouldn’t wish that life on anyone. being the only one of his kind, he thinks, is more a blessing than a curse.
unaware of each others’ existence, they discover their immortality separately.