"Sorry, I always forget what Jim tells me to do. "Stop mauling the clients" and all that. It's just so much fun to meet a new friend though! Have you met Jim? He's the best!"
Please do not confuse him for Matthew Batres. (Mathew!edit: What? How would anyone- Oh, yeah, the name thing. Never mind...)
After Tigress journeyed to New York for a martial arts tournament, she met Humphrey, who came to New York while attending a party she had been invited to by a fellow competitor. The two hit it off fairly well, and a couple rounds of drinks later, they became, ahem, significantly preoccupied.
The next day, she won the tournament, despite her hangover, and decided to stay fro a short time in New York. A short while later, she came down with flu-like symptoms. Passing them off as random illness, she continued to train. However, as time went by and she missed her period, it occured to her what had happened. After consulting Jim (owner of the Shady Abortion Clinic), she decided to keep the child. Deciding to keep it secret, she continued to train in order to hide her pregnancy. The only oddity was the occasional morning sickness and muscle spasm and Mathew shifted around.
When it came time to give birth, Tigress left the Jade palace in order to avoid discovery. When Mathew was born, she promptly handed him off to a wet nurse to be handled, coming to see him on occasion. Instead of bonding with the wet nurse, as most young children would, Mathew instead became fixated on his mother, treasuring these visits. When he was weaned, Tigress immediately sent Mathew to his father in Canada.
Kate, while ultimately unhappy with Humphrey, could not bring herself to turn the child away, and so adopted him, albeit grudgingly. When she could, she would send him off to spend time with his Aunt Lilly, who was far more understanding than Kate. This is where Mathew got his obsession with turtles. His half-siblings, particularly the older ones, were none too pleased with him, as they saw him as their father's favorite. While in truth, Humphrey loved all his children, it was simply that Mathew required a more overt showing of that love, and required the defense that his father provided against his step-mother.
Once Mathew reached his first year, Humphrey broke down and told him the truth; Kate wasn't his mother. While not particularly devastated, he was a bit saddened. After explaining who his mother was, and mentioning the clinic she had gone to, Mathew decided to venture south to New York and see what Jim could tell him about his mother. Jim did not have much to offer; he wasn't even entirely sure of where his mother had come from. So, instead of returning to Jasper Park, where it was obvious he wasn't wanted, he opted to stay with Jim, much to the man's exasperation.
A year later, a number of other odd individuals of similar backgrounds came into the Clinic, followed by an attack by Kurgan Junior, and then he and the group were thrown into an adventure that none of them had bargained for. (See The Salvation Arc for more details.)
Relationships with the other Mistakes
Mathew was initially mistrusting of Piper (due to comparing her looks to that of her mother, Sandy Cheeks, who is a squirrel, which he hates), though over time has warmed up to her. He is also fond of Dusk. In general he is fond of most of the other Mistakes, and is one of the few that does not openly dislike Dorian, Rowan, and Kainashi.
In a recent development, he appears to have developed a crush on Fawn. Only time will tell if it pans out.
(Mathew!edit: Stop telling random people on the internet about my business! They don't need to know that! And what if Fawn reads this?!)
Mathew is exceptionally ditzy, and generally treat everyone he meets as a friend, until proven otherwise. While it has been officially declared he can feel the full range of emotions, he has rarely been shown to be sad, or angry. He has been shown to be exceptionally protective of his adopted "pack".
Fourth Wall Sensitivity
Mathew has been shown to be aware of the Fourth Wall, and breaks it often, mentioning "viewers", and The Roleplayers, whom he reveres. He has also been shown to have a certain amount of "psychic" awareness of the the past and future, as well as knowing things that he wouldn't normally know, which he calls "looking at previous pages", "browsing the headcanon thread", and "getting a sneak peek". He also seems to just know things about what his roleplayer does or is doing on his computer.