When encountered in Boulder City, Jessup is holding 2 NCR troopers, privates Ackerman and Gilbert, hostage. He also accompanied Benny, and dug the Courier's grave before he/she was shot. He argued, albeit briefly, with Benny over the burial of Chance, whom he had watched out for since the onset of Benny's mission. Jessup was able to easily intimidate Benny into allowing the burial, as the other Khans backed his threat.
During many portions of the graphic novel he exhibits fierce loyalty to the Khans and, more personally, to Chance, watching over the troubled man as if he were a brother or son. It is no surprise that later in Boulder City he holds sway over them as a leader figure following the death of McMurphy.
ps3xbox360pc If you help Jessup get out of Boulder City without killing anyone (through the Speech check) he will say he has a long walk ahead of him, if you meet him at the Great Khan settlement in Red Rock Canyon, he will still say he has a long walk ahead of him. [verified]
pcxbox360 If you sneak into the Boulder City Ruins (through a Sneak check), Jessup will be found dead, but the Khans with him will still be alive. [verified]
pc Jessup and his crew will be hostile towards you when you kill the NCR hostages, even though you killed all the NCR for him to escape during Boulder City Showdown. This will also occur even when they aren't in the same area, meaning only Jessup and his crew will be hostile at Red Rock Canyon. [verification overdue]