Bartholomew "Bat" Velasquez is the second-in-command in Maia's werewolf pack in New York. Unlike his fellow werewolves, he does not live at the pack's headquarters, nor did he stop dreaming; instead, he has his own apartment and also pursued a career in music, working as a DJ at the Pandemonium Club.
When Maia Roberts first came to the city, he was one of her first werewolf friends, along with Steve and Gregg. Once, in a park, they ran into some vampires sucking on blood bags under a bridge. They got into a fight, then they witnessed the vampires ripping Gregg in half and eating him when his insides fell out.
Another time, two teenage boys armed with knives had tried to grab Maia while she was walking through Central Park one night after she'd first come to the city, and only Bat had kept her from killing them both.
At one point, he and Maia began dating. However, Maia told him that she wasn't ready for a real relationship, and Bat decided to break up with her and give her space, despite what he really felt. They remained good friends after that. He then began dating a "witch" named Eve, though the relationship did not last.
One evening in August 2007, Clary Fray and Simon Lewis partied at the Pandemonium Club before meeting the Conclave Shadowhunters for the first time. Simon had noted that Bat, the DJ that night, was doing an exceptional job.
One eventful evening the following month, Bat was sitting beside Maia when Jace Herondale walked into the Hunter's Moon, an underground werewolf bar. Bat and Jace soon began exchanging snide remarks. Bat, unable to contain his anger, swung at him and missed and was immediately sent away by the bartender Pete for a 'walk'.
Outside, he scarcely saw a strange figure kneeling by a cub, Joseph, whose throat had been cut open. He had unwittingly interrupted a man from draining the young lycanthrope's blood. Bat immediately returned to the bar to tell the others. Upon his return, Jace's reaction surprised them, especially since it had only been a week since the Accords was last signed.
When Jace used an unknown derogatory term for werewolves, a full-blown fight between Jace and some of the werewolves finally broke out, with Bat unsurprisingly making the first move. When Luke arrived to stop the fight, Bat was the only one still defiant and refused to let go of Jace. Only when Jace began to speak with Luke did he let him go.
The Dark War
When Simon dated both Maia and Isabelle in September, Maia confided in Bat and he gave her advice. He told her not to be so hard on Simon, who, aside from being a geek who haven't had much luck with women, seemed like a guy who would do stupid things when girls are involved. When Luke was injured in November, Clary and Jocelyn brought him to their headquarters. Despite the late hour, Bat, who was then the third-in-command, still happened to be there and helped treat Luke.
In December, Luke left for Idris as the werewolf representative on the Council. By then, Bat had become his second-in-command, and thus became the pack's temporary leader. As expected from him, Bat set up office in the Hunter's Moon.
While the pack waited for an update from their true leader, Sebastian Morgenstern had attacked and burned the Praetor House and had also killed most of the Praetorians. Bat was among the werewolves who responded to Maia's call for help. Maia, recovering from the shock, later told Bat that she was actually going to break up with Jordan on the day that he was killed by Sebastian but she kept putting it off. He comforted her during the funeral of the members of Praetor Lupus.
Shortly after the rescue, Rufus Hastings, a survivor of the massacre, began spreading discontent among the werewolves, saying Luke was more of a Shadowhunter than werewolf and that his loyalties lay with the Nephilim, and that Bat should also not be trusted because Luke appointed him. Because everyone was beginning to worry about Sebastian's threats against the Downworlders, some listened.
Maia, whose steadfast loyalty to Luke worried Bat, knowing Rufus may turn them against her, too, decided to confront Rufus. When Rufus hit her, Bat stepped in and ordered him to leave the pack since he was only a guest, an unwelcome one. Rufus immediately challenged Bat for the leadership of the pack, which he accepted, rather than risk losing face in front of the other werewolves. Bat admitted to Maia that he was nervous and knew that there was a big chance that Rufus could beat him. Wanting her safe, Bat tried to get Maia to leave town.
The fight was held the following night, in the southwest part of Long Meadow in Prospect Park, with Leila Haryana acting as the referee. Rufus was bigger and towered over Bat, though, to his advantage, he was lighter and faster. Rufus drew "first blood" when he sliced Bat's chest open with his sharpened claws. Rufus snapped Bat's wrist and knocked him out. Before Rufus could deliver the killing blow, Maia issued another challenge against Rufus, which was technically not allowed. Rufus accepted the challenge nonetheless and lunged straight for her. Maia threw dirt and grass in his eyes and temporarily blinded him. Taking the opportunity, Maia broke his foot and jammed her claws into his eyes, killing him. With this, Maia was proclaimed the new leader. After the fight, Maia checked on Bat, who was already beginning to heal. He spoke to Maia with some difficulty, finding it slightly humorous that she fought dirty.
Fully accepting of Maia as the new pack leader, Bat became her adviser, beginning with explaining to her the administration of the wolf pack. Soon, they found out from the warlocks Malcolm Fade and Catarina Loss that Luke had in fact been kidnapped by Sebastian. When Maia immediately called for a meeting with Maureen Brown, the head of the local clan of vampires, Bat was among those who accompanied Maia. He was surprised when she agreed to form an alliance with her against the Nephilim, especially when Maia let Maureen drink her blood to seal the deal. When it was revealed to have been a plot to poison Maureen planned by Maia and Lily, Bat, though shocked, did not question her decision and was even pleased with the outcome. Bat agreed to sit with Maia during her talks with Lily for their groups' alliance.
Afterwards, Bat went to the Beth Israel Hospital to help Catarina with a demon, which he and Maia were able to subdue, though with difficulty, proving the point Lily wanted to prove to the Downworlders—that they needed Shadowhunters to take care of their problem with demons.
Five months after the Dark War, Bat attended Luke's wedding to Jocelyn at Luke's farm. A DJ booth had been set up for him, though he mostly lounged around while the others played the piano in the main tent. At this point, Bat and Maia were both seemingly putting effort into resuming their previous relationship.
After the war, Bat participated in Maia's efforts to reestablish the Praetor Lupus. He was seen as an important part in the process as Bat had been able to maintain a life both as an active member of his pack and as someone with a human/"mundane" life.
Bat is a muscular and broad-shouldered guy at six and a half feet tall. He has dark skin, brown eyes, and a square jaw. He also has a thick scar along his right cheek where silver powder burned his face, and a crater-shaped scar on his right arm where he was shot with an ordinary bullet.
- City of Bones (first mention)
- City of Ashes (first appearance)
- City of Fallen Angels (mentioned only)
- City of Lost Souls (mentioned only)
- City of Heavenly Fire
- Born to Endless Night (mentioned only)