What if I Put Vladislaus Straud in Oasis Springs?

Depends. Will you be giving him the "Sun-Resistance" Vampire perk?

If not, they will need to stay inside (or on a covered porch) during the day. Otherwise, they'll die from exposure to the sun.

As far as the Seasons EP, I'm not sure, since I haven't gotten it yet (hopefully for my birthday this month).

Nothing happens really. They will venture out at night and stay indoor during the day. If you have Seasons, they will roam the streets with an umbrella to protect themselves from the sun. After a while, some will probably autonomously gain sun resistance. Vlad in my games usually ends up working at a food stall in San Myshuno.

I just want to find out what will he do in the location where there is lots of sunshine...

Try it and report back?

You would make the night shorter for him (in Forgotten Hollow, night comes earlier than in Oasis Springs). He would spend most of his time indoors.
He already has the weakness that will make the sun more dangerous for him. Good luck trying to reset his powers as you cannot get the sun immunity to him otherwise.

"Nindigo;c-16651759" wrote:
Nothing happens really. They will venture out at night and stay indoor during the day. If you have Seasons, they will roam the streets with an umbrella to protect themselves from the sun. After a while, some will probably autonomously gain sun resistance. Vlad in my games usually ends up working at a food stall in San Myshuno.

I placed a couple of vampires in my empty save (took out all the premades), then I decided I wanted to go ahead and build up some powers, so I saved them to the Library before deleting them; put them in a new save where I still had Vlad and the Vatores plus a vamipre I'd developed (they're her apprentices) and discovered they'd already developed some abilities even though I'd never actively played them, including full sun resistance, even though they were still technically minor vampires. Quite strange. :|

"bootsguy;c-16702514" wrote:
Can I make him human again so he will not be affected by the sun ever again?

1) Reach Vampire Lore lvl 15 (max)
2) Harvest 10 Garlic, 10 Wolfsbane, and 10 Plasma Fruit (easiest to find them growing in Forgotten Hollow neighborhood area)
3) Click on a bar to Make Drink --> The Ultimate Vampire Cure, which requires the ingredients above
4) Have the vampire you want cured drink it

"paradiseplanet;c-16702524" wrote:

"bootsguy;c-16702514" wrote:
Can I make him human again so he will not be affected by the sun ever again?

1) Reach Vampire Lore lvl 15 (max)
2) Harvest 10 Garlic, 10 Wolfsbane, and 10 Plasma Fruit (easiest to find them growing in Forgotten Hollow neighborhood area)
3) Click on a bar to Make Drink --> The Ultimate Vampire Cure, which requires the ingredients above
4) Have the vampire you want cured drink it

If the goal is only to make him sun resistant, you could just make a power resetting drink instead; it's a lower level recipe, and it lets you invest some of the points into having full sun resistance while still keeping him a vampire.

Sounds like a fun idea. Maybe Forgotten Hollow got attacked by an angry mob bc sims found out about the existence of vampires and now Vlad is in hiding in the place that seems the most unlikely for vampires to be in.
Vlad isn't enjoying his new modern home very much and longs for his historical mansion, but at least he has a secret basement to be gloomy in. The residents' plasma taste a bit dry, like a grape that was in the sun for too long. Oh well, it's better than being staked.

@bootsguy I've had a vampire in Oasis Springs before. Just keep him out of the sun and he'll do fine. :)