MalMal's manga / #Re-read(2)

Beta and Alpha are getting married and try to push past the trait difference. But the beta realizes it won’t work out he unalives and gets reincarnated. The beta is now an omega so he finds a suitable alpha and ends up pregnant with the child of three alphas.

Normal human is attacked by a vampire and another vampire saves him on a whim. That vampire is the boss of many others, and the human is slowly transforming into a vampire himself. Before that he is a Tank, a period of time where the changing human has a limitless amount of blood.