How did he come back??

Maybe bc of the promise he made, that since she saved him he shall forever serve her too

But fyodor took his body!

In a later chap he was glitching, maybe his promise bound him to turn to his shape shall the girl need anything

I wonder if he took over one of the other vampires? It'd be cool if so

Riiiiiiight

I know it's very very unlikely, but it'd still be cool ┗( T﹏T )┛ (and less bleak than the . . . other possibilities)