Larry is a human who was swapped with a changeling, leaving him in a state where he considers himself part-human, part-faerie, and part-wolf as he constantly shifts between the states. He serves as Jack's partner in the Jack Flash Detective Agency and as one of the protagonists of the short story, Jack The Flash and The Rainbow Egg (Part 1).
In his human form, Larry appears to be an ordinary teen that has rumpled brown hair goes down to his collar and has a pinkish face with freckles, but he has two pointy wolf ears. In his wolf form he's large and has grey fur.
Larry is somewhat similar to the teenage appearance that he has, being that he is easily distracted by things like his game and has favorite clothes. But he's well-mannered enough that he doesn't like the idea of running around without wearing anything in New York, due to how the transformation destroys them.
He doesn't like it when Jack treats him like a child and finds some of the things she does being overly complicated or theatrical, but she notes that when he focuses in on something he tunes everything else out.
Larry was taken by Fae when he was born and swapped with Jack, leaving him to be raised in their land and shifting due to the magic found there. One day he was curious and sought out Jack, which led to her understanding that she was a changeling and brought her over to the land of the fae. Since she felt she didn't belong, Jack returned back to the normal world and Larry came with her, staying in her apartment and helping with her agency.
The Golden Yarn
Larry bursts in through a window in the first case of the short story, Jack the Flash and the Rainbow Egg (Part 1), having arrived late to assist Jack due to the traffic and looking for a place to put his clothes so he could transform back. He is later seen in Jack's office, playing a game and eating pizza when they receive a visit from Vince, a centaur who works as a postal worker for New York.
They receive a leaf that has magic within it linking them to Lindel, who explains the case of the stolen eggs. During this time, his transformation begins to slip so Jack chastises him before telling him to clean up and head to bed early so they could resolve the case tomorrow.
Larry accompanies Jack to the theater where he feels uncomfortable due to being sensitive to the emotions that were steeped into the building itself, so she leaves him on guard duty when she investigates further with the ghost of Roderick Byne. He later comes when he hears movement and feels the presence of the dragon's egg, forcing them to flee.
- Wolf Transformation: Due to the magic of the fae lands transforming him, Larry can shift between Wolf and Human forms. Despite this, however, he is not considered a werewolf due to the fact that those are individuals who are born with that ability or are cursed into transforming. 
- In this state he's noted as being faster than any gun and his howl can shake the earth or clawed up from the bowels of hell, according to Jack.
- Jack: He went out of his way to find Jack after being raised by the faeries that took him, likely out of curiosity. Since then he has stayed with her, acting as her partner, through he dislikes it when she treats him like a child.