Inajira

Inajira the arcanoloth is a fictional character originally appearing as a villain in the Advanced Dungeons and Dragons Ravenloft adventure module, Roots of Evil

Biography
385 years in the past, Strahd von Zarovich was a battle-weary mortal human. This changed when he entered a pact with the arcanoloth Inajira, who in exchange for unknown services to be rendered in the future granted Strahd's desire to be unbeatable in battle. Inajira, fearing nothing from the mortal, granted Strahd's request to hold Inajira's Book of Keeping until the contract was complete. Upon changing Strahd into a vampire, Strahd was whisked away to the Demiplane of Dread, Ravenloft, depriving Inajira of both his prized Book of Keeping and the completion of his contract with Strahd.

Exiled in disgrace for the loss of his possession and failure to seal his pact with Strahd, he is incensed later when Strahd returns to the Prime Material Plane during the Grand Conjunction and vows vengeance.