Hunter is a kala of the Kastar Ghaash'kala. His resemblance to Warren, and Warren's late brother Hunter, is definitely purely coincidental.
Hunter was found wandering The Labyrinth about 20 years ago by a Kastar patrol, heavily wounded and covered in burns, with no memory of who he was or how he got there. He joined the clan after being healed by Sinnoch.
After the events of 21. Deadly Traps and Interpersonal Drama, it seems he is, in fact, Warren's brother.