From Edge of Darkness Wiki
Inferno p. 125
The Possessed is tended to by an animal guardian; it’s quite often a black animal, though it may also be an animal that is oddly-colored (an albino, for instance, or a creature whose feathers or fur shows patterns that are not common or ever found in nature). The animal is profoundly loyal, and will protect the Possessed at the cost of its own life (though if that happens, this Merit will need to be re-purchased). The character may still at times need to succeed on a Manipulation + Animal Ken roll to communicate her wishes (which are not purely empathic), but she gains +3 dice on this roll.
The number of dots purchased in this Merit indicate the general strength of the attendant hellfamiliar. One dot is usually equivalent to something small (such as a raven). Two dots represent an animal with similar traits to a cat. Three dots provide the character with a beast similar to a dog.