Mitch and Rick were two twin monsters,  when Mitch dies,  Rick brings him from the dead using a spell that had cost of body part. But Mitch changes and so does Rick,  thus Mitch became Mallory and Rick is Zabel. Now Zabel has hunger for blood and Mallory feels soulless,  and seems to act strange.

Mitch aka Mallory dies from a monster Hunter,  Rick aka Zabel escapes with his twin's dead body into deep cave of lost adventurers.

Another fantasy art:')