>Taking him to Troy in Vault City to be healed will get him purged of the various bullets embedded in his thick skin, which Troy will then give to the Chosen One. Giving 20 7.62mm, 40 .44 Magnum JHP & FMJ, 50 5mm JHP, 10 .45 caliber, 24 10mm JHP, 50 .223 FMJ, and 20 9mm ball. He has been shot by a lot of people. Note that this can only be done as Captain of the Guard, otherwise Troy will go hostile for someone bringing a mutant into the city.

http://fallout.wikia.com/wiki/Marcus

>{361}{}{My, your mutant friend had a great deal of bullets and shrapnel lodged in his body. It's a wonder he didn't have lead poisoning. I finally managed to get it all out. Here it all is.}

- Dr. Troy

http://fallout.wikia.com/wiki/VCDRTROY.MSG
https://pastebin.com/qEkfRyfH