Jessup is one of the Great Khan members hired by Benny to assist him in killing the Courier in Goodsprings. Jessup traveled with two other Great Khan members named McMurphy and Chance.
Jessup displayed great amounts of loyalty to the Great Khans and their warrior traditions, this is shown when he fights for the right to bury Chance after he was killed in a battle against the Fiends. Jessup is also one of the higher ranked members in the Great Khan tribe.
Along with Benny he and McMurphy were able to incapacitate the Courier and steal the Platinum Chip. They began following Benny until they came to Boulder City, where he and McMurphy joined some Great Khan members. It was in Boulder City that they were trapped by the NCR. McMurphy dies due to various injuries that he’s sustained causing Jessup to become the leader of the Boulder City Great Khans.
The fate of Jessup is decided by the Courier when he makes his way through Boulder City.