He is an avid role-player (as are most of the Alphas) and hosts a weekly game of Arcanos where Harry Dresden is an irregular player. After Kirby's death in Turn Coat, Dresden introduces Waldo Butters to the games.
He is an idealistic pessimist who believes that people are too incompetent to hurt themselves and each other as much as they do. Borden believes that the mortal response to the supernatural threat (ignore it or explain it away) is stupid, and he is outspoken on this belief.
In Turn Coat, Borden informs Dresden he's not doing anything blind anymore. If he wants the Alphas' help, he needs to be better informed. Dresden give him a CliffNotes version of the supernatural world with a promise of more later.
Billy Borden is first introduced as a college student who is part of the group calling itself the Alphas. They learned how to shapeshift as a werewolf from Tera West. Throughout the series he leads the Alphas in fighting against any supernatural threat in their area. Dresden calls on him and the Alphas from time to time in his own fight against bad guys. Over the years Borden matures and develops as a stand up leader, a good friend to Dresden and has solid loving relationship with Georgia.
In the series
In Fool Moon, when we first see Borden he's arguing with Georgia—Borden wants to go out tear someone apart, Georgia says they should follow Tera West's instructions and stay put. Tera returns and intercedes scents Harry Dresden and gets them all out. At the Full Moon Garage he and two other wolves circle around Agent Harris in Hexenwolf form keeping him from hurting any more of the Alphas or escaping. At Georgia's parents home, Borden tells Dresden that he and the Alphas are going with him to stop the Hexenwolves. There is a quiet romantic moment between him and Georgia. At Marcone's estate, Dresden gets separated from the others and when he gets near the clearing, he sees the werewolf get shot with a dart and all the other Alphas are down, too. Thery are all put in a giant pit and meant as the bait for the Loup-garou trap. After escaping, he and the others leave with Susan.
In Summer Knight, Borden has replaced forty of fifty pounds of fat with the equivalent in muscle, and is out patrolling with the Alphas. He meets Harry Dresden in Lake Meadow Park, just in time to be attacked by a couple of teens and a ghoul, which are rapidly defeated. He informs Dresden that a client is waiting for him at his office, whose appointment he has accepted on Dresden's behalf.
In Dead Beat, now has a beard that makes him appear older. He and the Alphas manage to save Dresden from Cowl and Kumori outside Bock Ordered Books by surrounding the two necromancers and driving them off. With Georgia acting as a driver, they all leave the scene for Georgia's parents’ house where Billy is convinced that he cannot provide martial assistance to Dresden this time due to the dangers. Billy and Georgia then drive Dresden back to the Blue Beetle, and Georgia lends Dresden her car as the Beetle has been trashed.
In Turn Coat, the Alphas are attacked by the Naagloshii. Kirby is killed and Andi Macklin Macklin is badly injured and in the hospital. The Alphas engage in the battle on Demonreach against the Gray men brough there by Binder and Madeline Raith.
In Aftermath, Billy Borden joins forces with Karrin Murphy after seven-months pregnant Georgia Borden has been kidnapped. They find her in a warehouse along with a number of prisoners taken by the Fomor, and rescue her from their control.
In Ghost Story, after Harry Dresden's death, he was a part of the Chicago Alliance and Paranet meeting. He seemed to have very little tolerance for Daniel Carpenter's immaturity. Like most other members of the Chicago Alliance, he seems terrified of Molly Carpenter. She once unleashed an illusion on him of creatures dragging him into the Nevernever, leaving him curled in a fetal position. He, Andi Macklin and Marci were part of Murphy's team that went to help rescue Mortimer Lindquist at the Big Hoods's hideout.
- Ghost Story, ch. 9
- Turn Coat, ch. 30
- Turn Coat, ch. 49
- Fool Moon, ch. 5
- Fool Moon, ch. 26
- "Something Borrowed"
- Fool Moon, ch. 25
- Fool Moon, ch. 28
- Fool Moon, ch. 29
- Fool Moon, ch. 31-32
- Summer Knight, ch. 1
- Dead Beat, ch. 8
- Dead Beat, ch. 10
- "Day Off"
- Turn Coat, ch. 5
- Turn Coat, ch. 38-43
- Ghost Story, ch. 10
- Ghost Story, ch. 46
- Jury Duty