Responses
You can try: https://www.mangago.me/tag/bisexual/ or replacing bisexual with vampire, many of them come up with lists whenever you check one specifically "These lists have this manga". Check this one: https://www.mangago.me/home/manga/list/happy_ending_kuso_kurae/1/ for Happy Ending Kuso Kurae the 1° result on the tag bisexual.
looking for a BL masc x masc, seke, they also like girls, lots of sexual tension slow burn, and completely consensual...bonus points if they're both hot vampires :-2