Etienne Rarnis is a man held captive at the Thalmor Embassy.
Crotch Guzzler encountered him while searching for a real party in the Thalmor Embassy dungeon.
After getting hit by one of Crotch's fireballs, he thought Crotch was attacking him and ran off.
Crotch followed him until he found Malborn lying dead at the top of the stairs. Crotch does not encounter him after this.