what'd be Vlads reaction to halfa Peri? Would he be trying to get him on his side?
It's important to note that this isn't canon to wings and wisps, It's a divergent au called the "Third Halfa au" where Peri becomes a half ghost.
This is also pre-Danielle.
Originally Vlad's intention for sending Skulker after Peri was to mess with Danny, Either distract him or cause Danny to fight him directly and get the DNA sample to clone him.
Peri's slow transformation into a halfa in this side au is caused by complications related to the shot from Skulker in the normal fic.
Surprisingly, I think it would cause him to take a step back, Vlad is capable of evil deeds and doesn't care to screw people over but to find out that he inadvertently caused someone to deal with the life changing effect of becoming a halfa.
It isn't enough to cause Vlad a change of heart completely but he does question some of his actions.
He hates Jack and blames him for the college incident, Blames him for Danny's incident but Vlad had indirectly did the same thing to someone else, A child none the less.
I think Vlad would hesitantly interact with him, And this would be sometime after their first fight, Which doesn't go well, Peri ends up biting him and then I imagine Vlad keeps his distance unless they get into another confrontation.