Bannon

Bannon is the owner of Potomac Attire and a member of the Rivet City City Council.

Bannon thinks that he is the most important person in Rivet City and when asked about the history of the city, he will tell you he is the founder. This is not the truth. But that doesn't stop him from telling you. He also apparently has a "social problem" (STD) as noted by Doctor Preston on his terminal.

Unmarked quest: Council Seat
Bannon mentions that his council seat is being contested by Seagrave Holmes. He wants you to look for incriminating evidence against his opponent, which can be found in Seagrave's room (under the bed, leaning against the footlocker). The key for the room can be pickpocketed from Seagrave.

Once you have obtained the evidence, you have to side with either Bannon or Seagrave Holmes. Denounce the other to Lana Danvers and collect your reward. If you complete the quest in Bannon's favour, he rewards you with Deathclaw Gauntlet schematics and a permanent 10% discount at his shop.

Medical Information
Bannon's medical information may be accessed from Doctor Preston's terminal in the Rivet City clinic.

Bugs

 * For no apparent reason, Bannon can be found locked inside Dr. Li's room at Rivet City at any point during the game. If the player has already escorted Dr Li to the Citadel there is no way to rescue Bannon without lockpicking the door. If you do not lockpick the door he will remain inside indefinitely and can be heard shouting "Is anybody there?" This might have something to do with Bannon being one of the possible 'sleeping partners' of Dr. Li (along with Sister, and several other male residents - not all at once!). Whether this is a bug or a humorous Easter Egg is debatable.

Messing Up the Store
If you turn in Bannon for trying to blackmail Seagrave Holmes for the side quest, he will jack his prices up and buy products off of you for less caps. Although there is no reaction from Bannon, it is fun to mess up his store by knocking off all the items off the shelf for trying to rip you off.

Appearances
Bannon only appears in Fallout 3.