Lucilion tends to be a pretty nice, peaceful kind of guy, but wound up in a situation where he had no choice but to feed on the blood of those around him. That being said, he decided to peacefully go and search for a willing participant who would allow him to drink their blood and also create a relationship of some sort. The requirements are pretty basic; The person must move to The Rebellion of Terminus and cannot be 'captured/forced' into it, UNLESS forced to become his blood slave by someone else that Lucilion has no connection to. Keep in mind, your character will be treated with respect and will be well taken care of. Recommended age would be 6 months or younger.
I think it would be unique if he had a contract with someone who decided to sacrifice one child from their litter to become his blood slave. With this idea in mind, the kitten would never know who it's real parents were, only that Lucilion raised them. However, he'd allow them to have a connection with each other by taking the child on family visits. This contract would have to be due to a friendship, or just out pure hatred for the litter. In that scenario, it is up to you if you want family visits.
Unless, your character is charmed by Lucilion just enough that they become his source of blood. He'd still treat them with the same respect and care, but your character could feel/have any opinion toward him. Please remember, he treats them very kindly and takes very good care of them. However, I am asking that your character has at least a slight submission, or stockholm's syndrome.
Note; His fangs are longer than normal so any willing character, who was not forced into/born into being his blood slave, must have a high pain tolerance.
It really is up to you on which idea you choose and if you have another idea that relates, reply with the information and it just might work out! :)
Short description of Lucilion;
Lucilion Wraith-Gaudius was born to Sayaka/Evergreen Wraith-Gaudius, his mother who had been mates with his deceased father, Vandeadcarnival. He never knew his father, an ex-leader of The Rebellion of Terminus, but was raised by his mother who later became the leader during his young childhood. He is of HP with HPR, being a 5 Star Elite for his clan. He is pansexual, sized to be smaller than the average male and almost as petite as a female. He has black fur and amber eyes, which turn red after a while of feeding on nothing but blood. He is currently 6 months old.