Ok, something is wrong with this quest. I am being sent by the NCR to stop the violence caused by the Kings. I decided to not kill Pacer so I talked to the King. He said he would help if I did favors. First favor was to get myself hired by some mercenary near the Strip gate. I remember seeing him before so I went back to the gate, but now he is gone. I've waited about 3 days now and he's not showing up. The only options shown in my quests is to kill Pacer or tell the Ambassador I failed. What happened to the option to get hired by the mercenary? The King even game me 200 caps to hire the guy.

Thanks.

Have you tried switching quests to "G.I. Blues", and then following the quest marker?