The Legend of the Star: Sometime after the player has picked up their first star bottle cap, they will encounter a man who claims he has been following them. Holmes is a retired trader who noticed you had the same interest in the bottle caps that he collected long ago. He also mentions that if enough caps are collected, the treasure can be claimed from someone named Festus.
After speaking with the player, Malcolm Holmes will walk directly to the Mojave Outpost. He will disappear from the game once he arrives there. Since he has 6 star caps on him, one should try pickpocketing or killing him after the conversation ends.
Malcolm is carrying the roving trader hat and roving trader outfit; both of which are valuable for players to increase their trade profit and pass Barter checks at the lower levels where one is likely to encounter Holmes.
He will appear on the Scavenger platform if you wait long enough. After talking to you he swims directly off, no matter if the water has been cleared of Lakelurks or not.
If attacked but not killed, he will pursue the player for a considerable amount of time, occasionally going as far as Primm before being killed by the Powder Gangers there.
If you run the Nellis Air Force Base artillery gauntlet shortly after obtaining your first Star cap, be sure to comb the artillery field after making peace with the Boomers, as he may have been killed trying to reach you during the bombardment.
Even after he has been spoken to, most people and creatures will ignore his presence.
If you trade with Malcolm Holmes, the caps dropped after killing him will not increase. Also, if you buy the .308 rounds from him, they will no longer be in his inventory upon killing him or pickpocketing.
Trading with him and reverting to a previous save randomizes his shop inventory. (PS3)
"Nah, I gave it up years ago. Too dangerous. And even if I did still collect them, I'd tell you the same. There's people out there so mad with the idea of treasure that they'll attack strangers just on the suspicion that they have some of those caps."
"There's an old wasteland legend that says somewhere out there is a fabulous treasure from before the war.Those caps with the blue star on them, the tale goes, are the key to that treasure. They're called Sunset Sarsaparilla Stars. "