garrus is a latex liquidshifting snake, and he forces his victims to "wear" him as a suit so he can drain their energy. He needs to feed every so often to keep himself going, and this is one of the ways he does it. It doesn't harm the victim, but it does certainly leave them drained for a day or two once he finishes with them. He can exert a degree of control over their physical bodies and make them do things like have sex with others, or he can even pleasure them using his latex properties to feed off their energy faster. :o

Art ©  skulldog
Garrus ©