Ace

Ace is the vocalist front man of the band Ace and the Diamond Dogs and long-term friend of Elliot Hong. His birthday is October 31st and he's 22 at the beginning of the comic. He is Cambodian, but was adopted and is not aware of that fact.

Pre-comic
In high school, Ace was Elliot's best friend. Elliot was in love with him, but he didn't reciprocate, instead being interested in Elliot's brother Marcus.

Some time before the beginning of the comic, he formed a band with Elliot, Madina, and Kate.

He and Elliot have been dating on and off.

Theories
While currently unproven, there is substantial evidence that Ace is the villain known as Crank. They have numerous physical similiarities including the same haircut and skintone, both having double-pierced ears, as well as most identifying marks that Ace has (tattoos and piercings) being covered by Crank's outfit.

Additionally, Ace got punched in the chin "at work" the same night that Elliot punched Crank. The discussion he had with Kate in chapter 3 is also suspicious, as if he and Kate worked in private security as they claim, she would have no problem explaining to her mother where she got her money, and she likely wouldn't have enough to fully pay her mother's medical bills. Ace and Crank also seem to have similar attitudes. Both Ace and Crank have referred to themselves in the third person as "Daddy".

Alex noticed many of these similarities upon meeting Ace in chapter 8 and asked Elliot about it.

Additional facts

 * "Ace" is a nickname. His legal name is unknown.
 * Assuming the theories that Ace is Crank are true, Ace is a super.

Quotes
"Madz has to go do some vague science shit."

-Ace to Elliot about Madina