Very little is known of Joaquin's life. He currently resides on the southside of town, and some time prior to the start of the series he joined the Southside serpents, a dangerous biker gang of criminals and thugs.
Unlike his unruly fellow gang members, Joaquin attended the Twilight Drive-In to enjoy the film, and he did so, until he noticed Kevin Keller, shushing at them to quite down from several feet away. With Kevin in sight, Joaquin followed him to the food stand, in which a brief confrontation took place. Moments later, the two are seen making out in a back ally, behind the drive-in. Before leaving, Kevin gave Joaquin his phone number, almost immediately, he noticed Kevin's last name was Keller, as in the sheriff's son. As to be expected, he was alarmed by the revelation, but not frightened off, in spite of the fact that he's a gang banger. 
Upon learning that one of Kevin's friends had been attacked on the Andrews Construction work site, possibly by a Serpent, Joaquin agreed to assist them in gaining access to a known Serpent hang out called the Whyte Wyrm. He first reminded Kevin Archie, and Moose to play it cool, and to keep eye contact to a minimum. The plan was for them to find the guys that ambushed Moose, and call Sheriff Keller, but Archie took it upon himself to confront the potential attacker, who was a Serpent named Mustang. Joaquin warned Archie to back off, but he didn't, which led to a brief altercation that was broken up by FP Jones, the leader of the Serpents. Later that night, he joined FP at his home in the trailer park after discovering that the police had learned of their arrangement with Jason Blossom. The heat was on, so FP packed Jason's varsity jacket in a bag, and tossed it to Joaquin, to hide in a safe place as insurance, in case everything went to hell.
It was then revealed that Joaquin's relationship with Kevin was only a means to an end, they planned on using Kevin as an inside line to the Sheriff. However, Joaquin felt guilty as Kevin's feelings for him were genuine, but FP reminded him that they all had a role to play, even him.
Despite having earlier established that Jughead's 16th Birthday Party was suppose to be inner-circle only, Kevin invited Joaquin to the party, who he claimed was inner-circle because they were dating. Unbeknownst to neither Kevin nor Veronica, Joaquin eavesdropped on their conversation pertaining to her father's trial and his potential involvement in Jason Blossom's Death. As Jughead and Betty entered the house, everyone jumped out yelling surprise, then Kevin introduced Joaquin to Jughead. Then came the birthday cake, as Joaquin, Kevin, Archie, Veronica, and Ethel surrounded Jughead while he made a wish and blew out the candles. This small and quiet event quickly escalated into a full blown house party as the party was crashed by Cheryl Blossom and Chuck Clayton, along with many of their classmates.
Joaquin and Kevin did not allow this to put an end to their good time, and proceeded to make out in the kitchen, until they were interrupted by FP, who asked Joaquin to show him to the bathroom, which was merely an excuse for them to talk privately. He informed FP that Hiram Lodge's daughter was also at the party, during which she mentioned her father possibly being connected to Jason's murder. He was then ordered to find out what the Sheriff knew, and to do that through Kevin. Unperceived by either of them, they were being watched from the next house over by Alice Cooper. Downstairs, Joaquin watched quietly as a devious gamed of "Secrets & Sins", took place, however, the game quickly turned violent between Jughead and Chuck Clayton, which resulted in FP bringing an end to the party.
Joaquin has a slim build, with tan skin, medium-length black hair, and almost silver-like eyes. At first glance, he comes off as grungy and dangerous, the fact that he is affiliated with the Southside Serpents, doesn't help. Apparently, when joining the gang, members are required to tattoo the gang's symbol of a serpent on their body. He possesses a very threatening demeanor, one that initially terrified Kevin Keller.
Admittedly, Joaquin is a member of the Southside Serpents, however, while he can be intimidating, he does not appear to be as ruthless and savage as his fellow gang members. He has a conscience, as evidenced when he revealed to FP that he felt bad for stringing Kevin Keller along into thinking they had a genuine relationship, as Kevin had real feelings for him. Joaquin is also fairly calm and relaxed, even under the most dangerous of situations, like leading Kevin, Archie and Moose into a Serpent inhabited bar.
- "Chapter Four: The Last Picture Show"
- "Chapter Eight: The Outsiders"
- "Chapter Ten: The Lost Weekend"
- Unlike most of the other characters, Joaquin is not a character from the Archie Comics.
- ↑ Grassi, Michael (writer) & Piznarski, Mark (director) (February 16, 2017). "Chapter Four: The Last Picture Show". Riverdale. Season 1. Episode 4. The CW.
- ↑ Cohen, Julia (writer) & Katzenberg, David (director) (March 30, 2017). "Chapter Eight: The Outsiders". Riverdale. Season 1. Episode 8. The CW.
- ↑ Lundin, Britta & Paterson, E. Brian (writers) & Wilkinson, Dawn (director) (April 13, 2017). "Chapter Ten: The Lost Weekend". Riverdale. Season 1. Episode 10. The CW.