I read a manga years ago about 2 boys who originally began as friends. I think one of them found/was found by a vampire nearby and was turned under some circumstance, I'm not quite sure though. Later after a time skip the other boy turned out to have become a vampire hunter. Kinda gave shounen ai vibes but I'm not sure if the manga was marked as such.

I'm pretty sure the manga was based on a novel series but again it was years ago so I can't remember clearly.

Thank you for any help!

Owari no Seraph?

Unfortunately no, though I really enjoyed owari no seraph as well. I believe the setting was more western style and the manga/novel is older.

Sounds like
Vampire and Hunter

Unfortunately not this one either but it seems interesting!