Khael
The Wizard Michael was a politically powerful and the most advanced Demonologist Horace found in the Wizards Guild, and the only one actually willing to risk expulsion (and possibly death) from the Wizard's Guild to attempt summonings.
Smart and paranoid, he caught Horace spying on him. Livid at being spied on and afraid for his own life and career, set about to destroy Horace. Horace avoided total expulsion from the Guild, but was banished from the Guild proper.
Upset at the loss of one of the most promising students in years, the Inner Circle of the Guild sent Michael to retrieve Horace so that he could (hopefully) be salvaged as a Guild Wizard. Michael tracked Horace as far as the the Abernathy Castle before he completely disappeared.
During the upheavals caused by Drain on Kardia, Michael successfully summoned Khaelaris, a Kaeven, which bonded with him. Deformed by fire during the summoning, the amalgamation called himself Khael.
The megalomaniacal Khael settled in a keep in the Titan's Wall where he proceeded to experiment on animals and kidnapped refugees with a perverted form of healing magic. He was perfecting the ability to take a power from an animal or person and transfer it to himself. Through a ritual involving skinning his victim, he successfully transferred power temporarily and was close to doing so permanently.
Khael encountered Horace and the other adventurers when they hunted down a party of his slavers. He left the young girl Jillian skinned alive as a warning to the group, and then captured Horace when he incapacitated himself trying to save her.
The remainder of the party tracked Khael back to his fortress, filled with the wild creatures he had created. Horace nearly broke free with a spell that virtually killed Khael. The Khaelaris kept Khael's body alive and attempted to finish the ritual skinning. Xandessa decapitated Khael as he plunged the knife into Horace.
Khael was dead, but Khaelaris transferred its being into Xandessa's sword. Only able to survive in someone gifted, at its next opportunity it escaped into the Wizard Umberland.