Liath is a tuxedo cat with very dark grey and white fur, a tail, and orange/red demonic horns growing outwards and downwards from his head. He wears a red loincloth and sash with a white rune and a matching red scarf around his neck which frills out on both ends with tattering and holes in the fabric. Liath has a rather feminine face, with long eyelashes, mascara, indigo eyeshadow over his red eyes, and pouty lips.
Liath is encountered at the very end of the Forbidden Bayou on the far right. Right of the exit to Smol Beach. He currently resides in some kind of wooden hut or shrine. Liath claims to be some kind of magic user, specializing in the brewing of magic potions that he or Joe can potentially use for various reasons. However, his Cauldron is missing and so he can't make anything really though his willing to at least have sex with Joe. The implication is that Full Frontal Frog are planning on have a complex new mechanic introduced via Liath's Potion Making Skills but it is not finished yet. Either that or they simply did not render his cauldron yet.
As of version 0.16.500, has demonstrated his magical abilities while having sex with Joe. Being able to transform himself into a perfect doppelganger of Joe and being able to produce a perfect clone of himself.
Beyond a sex scene, Liath doesn't seem to have another role in-game yet.