|The following is based on Van Buren and is not canon.|
After getting to know the Rusty Hooks for a bit, the player can find out that he can challenge the current leader (in this case, Kyle) to a fight (unarmed only) and whoever wins becomes the new leader of the Rusty Hooks.
The one caveat of the current leader is that he may choose anyone to be his "champion," and Kyle will always choose his favorite super mutant, Bear. After the challenge, the fight begins. Good luck! If the player wins the fight, he is the new leader of the Rusty Hooks. However, Kyle might be so pissed after Bear losing the fight that he triggers Bear's heart bomb – hopefully the player is not too close.
Character type completion breakdown
Combat Boy, Diplomacy Boy, Science Boy, Stealth Boy – Straight up and fight. One thing the player can do to improve his chances is to speak to Bear first, work up a rapport, and ask him to take a fall. He will tell the player about his heart bomb and will refuse to take a dive until he can be assured that the heart bomb won't go off if he loses. See other quests, Disable Bear's C4 Heart Bomb, Disable Trigger of Bear's C4 Heart Bomb, Rewire Trigger of Bear's C4 Heart Bomb to Explode. If he is assured the heart bomb won't go off, he will take the fall, no finagling required.