This question is RIGHT up my alley, as Vampire 
Miyu is my favorite manga and Larva my favorite 
character from it! (umm.. whats the question?) 
Seriously Drac is right when she says TV Larva 
is closer to manga Larva than OAV.  Though I 
would say Larva talks even more in the manga 
than he does in the TV series. (I own and have 
read the entire series in Japanese) Basically 
his story is something of an amalgamation of his 
OAV and TV selves:

He came to kill Miyu, but couldn't bring himself 
to do it.  Instead he ended up just sort of 
watching her grow up from a very young edge, 
putting off the job of killing her again and 
again.  The idea had been for him to get rid of 
her before her vampire blood awakened and she 
became the Guardian.  However due to his putting 
the job off she ended up awakening first and 
biting him, thus binding him to her as her 
servant.

Does that answer the unanswered?