Symbiote

Naomi kept her distance, unwilling to sit.  The gleaming black eyes of the furred predator flashed at her from within Sam's jacket.

"It's not like he wants to kill you," Sam said.  "It's a mutually beneficial relationship.  I get rid of waste and excess, and he ensures a steady food supply.  He only eats what I don't need."

Naomi tried and failed to keep her eyes from drifting toward Sam's left hand, where two fingers were sheared off at the knuckle.  A bandage peeped out from beneath his shirt when he moved.

"You'd be surprised what's actually necessary," said Sam.