Murphy was an amateur scientist even back in his pre-ghoul days, and his tenacity has allowed him to deal with his "affliction." He's close to making some real caps with his invention - an enhanced dose of jet that can keep a ghoul up and peaking, as jet "doesn't affect ghouls much".
He has an assistant named Barrett, who acts mostly as a bodyguard, but can also be seen assisting him with other tasks.
If you berate Murphy in dialogue, he will end the conversation. If you start another conversation with him and ask him about the Sugar Bombs, he and Barrett will turn hostile once the conversation ends.
xbox360ps3pc Sometimes it will take a few seconds for the game to register that you've given Murphy any or all of your Sugar Bombs. You'll say "Here's all the Sugar Bombs I've got.", but you won't receive any caps nor will they be removed from your inventory. Trying this a few times, as well as waiting for up to 30 seconds before speaking to Murphy again, seems to get it to work. [verified]
xbox360ps3pc If you have Fawkes in your party, Murphy will turn hostile towards him and Fawkes will kill Murphy. [verified]
pcps3 If the ammo is pickpocketed from Murphy and then in turn his weapon as well; after 72 hours both the ammo and weapon will respawn inside his inventory. This bug, however, does not replace his inventory with his old one; thus if you reverse pickpocket items into his inventory they will not disappear. [verified]
xbox360 It is very rare, but sometimes after you kill Murphy, and then steal something off of a shelf or from his area, a sound byte of him yelling "Stop, thief!" will play even though he is dead. [verified]