Didn't feel like doing a text write-up on the page. This is the Angler, a Purposed Lizard who's mission it is to protect another Slugcat on their journey.

The bulb on their head is a Data pearl that has many uses such as taking field recordings and providing Light. The Angler is much more akin to an overseer than a messenger, except Angler's purpose is to be a lot more protective of the Slugcat they follow.

The general lineart for this was taken from a base by Auxiliary_Cord