Mostly appearing in mists or dense fog, Felix tends to bring the eerie or creepy aspect to his arrival. His pawsteps are silent; you wouldn't know he was there unless you actually saw him. His "scars" still bleed sometimes if he's too rough but the pain doesn't seem to bother him. It kinda helps when you're soulless and emotionless, crazy even.
He can grow as many tails as he wants but they are disconnected from him so if someone were to pull them, they could seem to come right off and disappear once far enough away from his body. He bleeds red blood but if it were to hit the ground, it becomes black mist that disappates upon contact.
Two mouths allows for two ways to feed. His bottom mouth has a black hole inside of it, allowing him to do what he wants with what he stuffs there. Although it seems small, it's a plenty big enough place to hide a decent meal. His upper mouth is where he speaks more often and is the same color as his nose: black and dark purple inside. There is no esophogus and no organs to speak of with him besides a brain and eyes. The "X's" middle point is his actual pupil and when he looks away, the outer reaches of the "X" stretch to wherever he's looking; they always connect together.
Big ears means he can listen to anything and hear everything. He knows when he's been found, if someone is following him, where to find his prey all through his ears.
His claws are always out and always sharp. Regardless of how long he's been around, he is never seen without sharp claws. Whether he himself sharpens them or they stay sharpened, no one knows; they just know to never be caught within them.

Felix eats while you sleep. He basically eats your dreams, specifically your good ones; he can tell by putting a tentacle tail through your head and watches your dream. . If you're having a delightfully good dream, he'll eat it all and leave you alone; otherwise, he turns it into a bad dream. If he finds that you're having a bad dream, he increases the terror until you wake up. Once you wake up, you're mostly done for; he'll torture you with his tail. You see what he wants you to see and if you don't do what he asks, he takes your soul out of your body, killing you instantly.
He relishes in the insanity and horror; it's why he'll either eat your good dreams (to make him eat well and cause you to wake up soon after he's gone when the dream becomes infected) or just eat "you" (to make him feel good).