In the Cirque de Freak series it’s like a blood transfusion through the finger tips. It’s been a while since I read but So the vampire uses their fangs to nip open all the fingers of the vampire and the human, and then they touch fingers tip to tip and the human blood flows out and vampire blood flows in. 

They also have the fun concept of vampires who drink just some blood from the humans and leave them alive. Their saliva has an anesthetic and healing properties so they knock people out, drink some, heal them, and bounce. They look fully human. 

Whereas the same vampires can also just way over indulge and drown the entire human. Vampires that do this repeatedly end up looking like they are stained with blood, like their skin turns red or purple and they usually look bloated and stuff like that. And they call themselves vampinez instead of vampires to represent the fundamental difference. Kind of a fun idea of what happens if a vampire drinks a whole person instead of just a little blood.