Confidence Man

Confidence Man is a quest in Fallout 4, where you help the Diamond City Radio personality Travis Miles gain confidence by setting up a staged bar fight.

Quick walkthrough
This quest is given by Vadim in the Dugout Inn after the player has encountered Travis at the Diamond Radio Station in Diamond City. You will have to wait until an NPC like a guard tells you that Vadim was looking for you at the Dugout Inn before you can start the quest. The quest is to boost Travis' confidence. This will change how he speaks on the radio.
 * 1) Talk to Vadim. He will tell he's going to stage a fight to Boost Travis' confidence.
 * 2) Vadim will have the player character come back at 6:00pm to stage the fight.
 * 3) Speak with Travis and convince him to stand up for himself.
 * 4) Defeat Gouger and Bull and talk to Vadim.
 * 5) Vadim will have the Sole Survivor set up Travis and Scarlett, the waitress, to once again boost his confidence.
 * 6) When the player character returns from speaking with Scarlett, Vadim will have been kidnapped by raiders. They're holding him at the Beantown Brewery, north of Diamond City.
 * 7) Speak with Travis and he'll ask to come along.
 * 8) Meet Travis at the Brewery and clear out the raiders inside.
 * 9) Find Vadim in the back room and speak to Travis again.

Bugs

 * There is a glitch that causes both Gouger and Bull to be set to essential, making the quest impossible to complete without the use of console commands. A possible fix is detailed here