He was once a prison inmate alongside Archie at Leopold and Loeb Juvenile Detention Center, both of whom, along with many others, were entangled in Warden Norton's illegal fight club. Mad Dog was Norton's most cherished fighter, that was until Archie arrived and took his place. After he suddenly disappeared following a riot in the yard, Mad Dog returned to help Archie escape.
After Mad Dog helped Archie escape, he was taken back to Leopold and Loeb, where he remained for several more months, until calling Archie to tell him that the center is closing and they were all being relocated to Hiram Lodge's new prison on the Southside. Fortunately, with the help of Veronica, Archie manages to get Mad Dog and the other inmates pardoned after blackmailing the Governor. And so, Mad Dog returned to Riverdale, where he found his grandmother and little brother and later agreed to fight for Elio Grande in exchange for payment and housing.
Mad Dog is escorted to the pit to fight Archie, who is the latest to be "tapped". Archie’s been under the impression that Mad Dog was dead, asking where he has been, but Mad Dog only responds by punching Archie in the face. Mad Dog continues to strike a weakened Archie, though it would seem that he is very much still an ally despite the fight. He encourages Archie to hit him back. Instead, Archie grabs onto Mad Dog in order to talk to him without anyone noticing. Archie explains that there’s a plan in place. Veronica will cause a commotion and Archie will make a break for the drain under the ring. He wants Mad Dog to join him. Mad Dog then break the hold. He doesn’t believe that Archie will make it, especially after getting shivved, but nonetheless, he is willing to help Archie escape by providing him with a head start.
Before long, Veronica executes her plan and the ring is filled with smoke. When it does, Archie makes his escape. He tries to take Mad Dog with him but it would never work. Mad Dog had tried to get through the drain before and failed. He tells Archie to go without him. He will stay behind and hold off the guards. Hiram watches from the crowd, alerting the Warden that Archie is getting away. With this being so, Warden Norton tells the guards to apprehend Archie, but they fail as Archie makes it through the drain while Mad Dog fights the guards. 
Mad Dog calls Archie from L&L to ask for his help. Archie visits Mad Dog at L&L, who reveals that they’re finally shutting down the detention center. They claim the shutdown is because of what happened to Warden Norton, but in actuality, it's because they’re opening Hiram’s new prison on the Southside. Apparently, a wing of the prison will be designated for juveniles. They’re all being transferred there, and the L&L guards who made them fight, they’re all going to work at Hiram’s prison too, where they can restart the fight club. Even more suspicious, Mad Dog’s parole hearing was suddenly canceled. As well as Baby Teeth's and Thumper's. Mad Dog tried to call his family, but no one is answering. Considering that Mad Dog risked his life for Archie to escape, Archie assures him that he won’t step one foot in Hiram’s prison.
With Veronica's help, Archie manages to get Mad Dog, Baby Teeth, and the others free by blackmailing the Governor. Now that they’re out, Mad Dog plans on finding his family. However, some of the other guys have no place to go, like Baby Teeth, who has no one. Fortunately, Archie has the gym and is more than willing to allow them to stay in it. He then introduces them to Tom, his trainer. Archie hands Mad Dog a pair of gloves and offers him a rematch.
Archie boxes with Mad Dog at the gym. They are joined by Elio, who is unwelcome in Archie’s gym. Elio heard the gym reopened and through that he should drop by after learning that all the fighters from L&L’s fight club are with Archie. Elio claims that he’s a boxing manager looking for new talent. So, the moment they’re ready to start making some real money, Elio tells them to come see him at Casa Grande Gym.
Archie and Baby Teeth are joined at the diner by Mad Dog, who finally found his grandma and little brother, but they moved into an apartment building that’s falling apart. It’s been taken over by the Gargoyle Gang as well. They’re cooking drugs out of some of the vacant apartments. Archie assures Mad Dog that they’ll get the Gargoyles out.
Mad Dog, Archie, Jughead, Sweet Pea, Fangs, Baby Teeth and the Serpents rally in the gym as they prepare to infiltrate the Gargoyle Gang's apartment building. Thanks to Mad Dog’s recon, they have a pretty decent idea of the layout. The gang head into the building with Baby Teeth waiting outside as lookout. Armed with weapons such as crowbars and baseball bats, they make their way further into the apartments. The Serpents take 2nd floor while Archie, Mad Dog, and his guys take the 1st floor. Jughead’s off on his own on another floor. He encounters a Gargoyle, who immediately opens fire, forcing Jughead to take cover. As the gunfire goes off, the Gargoyles run out on both floors and immediately multiple fights break out in the halls and chaos ensues. Mad Dog, Archie, Sweet Pea, Fangs, and the Serpents, are all forced to fight.
After Mad Dog, Archie save Jughead from a Gargoyle, about half a dozen more appear. Mad Dog agrees to hold them off while Archie and Jughead find the cook. Not long after, Archie and Jughead make their way back into the hallway to find Mad Dog still fighting with the Gargoyles, and so Archie decides to help him out, leaving Jughead to get Kurtz out on his own.
Archie informs Mad Dog that Baby Teeth has yet to resurface since the raid, forcing some of the guys to go looking for him. Archie asks about Mad Dog’s family. He tells Archie that they’re fine. But they’ll be even better once he gets them out that building. Mad Dog has a new place, unfortunately it comes with the cost of fighting for Elio, who hooked him up with a house on the Northside. Archie insists that Elio can’t be trusted, but Mad Dog has very few options. And while this may not be what Archie wants, Mad Dog will always remember what Archie did for him.
Mad Dog enters the El Royale Fight Club and interrupts Archie's speech to add that he’s honoring Baby Teeth by dedicating his upcoming match to Baby Teeth. Mad Dog then informs Archie that there’s an upcoming boxing tournament this weekend, the Gilded Gloves. It’s now time for the fighters to weigh in. Mad Dog attends. Randy Ronson weighs in at 159 lbs while Archie weighs in at 154 lbs.
Mad Dog gives Archie a heads up that Randy is juicing, but not with steroids. Some kind of new powder that he saw Elio give to Ronson. It made him crazy strong. Mad Dog looked into Randy’s eyes and all he saw was rage. Mad Dog fears that Randy may kill Archie in the ring, which is why he has brought Archie drugs to level the playing field. However, Archie is opposed to taking drugs. Mad Dog leaves the drugs with Archie just in case he changes his mind.
Following the fight, Randy Ronson is taken to Riverdale General Hospital, where Mad Dog, Fred, Tom, Josie, Archie, and Veronica sit in the lobby, waiting to hear news of his fate. Just a few feet away sits Elio with Randy’s family. Unfortunately, Dr. Patel arrives to deliver the news that Randy did not survive. As he proceeds to take Ms. Ronson to claim the body, Archie and Mad Dog inform Dr. Patel that Randy was on drugs and that Elio was his supplier, though Elio claims to have had no knowledge of any substance abuse, which Archie, Veronica, and Mad Dog know to be untrue. Mad Dog states that Randy’s blood is all over Elio’s hands, though Elio retorts that it literally all over Archie's.
Mad Dog calls Archie to ask about the drugs he gave him because the police just raided Elio’s gym with a warrant, and they’re likely to do the same with El Royale. After Archie says they're in his locker, he and Mad Dog meet up at the gym to recover the drugs and dispose of them. However, before they can get the chance to do so, the police raid the gym, catching Archie and Mad Dog with the drugs in hand. And so, the two of them are arrested on site.
Veronica bails Archie and Mad Dog of of jail. Mad Dog insists that they’ll pay her back, though that’s the least of their worries as Elio has flipped Randy’s death on Archie. Archie, Mad Dog, and Veronica head down to Pop’s, where they watch the news report of Elio claiming that Archie provided Randy with the drugs that killed him. It’ll be a nearly impossible task to prove that it was in fact Elio who gave Ronson the drugs and that he’s setting Archie up. However, Veronica has a plan, which starts with a drug test for both Archie and Mad Dog. Afterward, Veronica holdS a press conference outside of Pop’s to announce that Archie and Mad Dog’s drug tests have come back negative. Randy’s sisters, Ms. Ronson, led by Elio, interrupts the press conference and accuses Archie of murdering Randy. Archie swears that he didn’t kill Randy, but if he could take back what happened, he would. However, the Ronsons are still distraught over Randy’s death, and his sister slaps Archie. Again, Archie apologizes, saying that he wishes it could’ve been him instead of Randy.
Mad Dog calls Archie into the ring as he needs a sparing partner. Veronica advises him to get back in the ring or he never will. Archie believes that may be for the best as he doesn’t want to be known as the Riverdale Reaper. Veronica says to Archie that he made amends with the Ronsons the best way he could, and now it’s time to look into the future. Archie’s not Riverdale’s Reaper. If anything, he’s it’s red hope. Veronica pleads with him to pick back up his gloves, and so he does just that, joining Mad Dog in the ring.
While sparring in the ring, Mad Dog and Archie are approached by Veronica, who comes baring good news. She has Archie’s fight application for the regional tournament. All Archie has to do is get one of his parents to sign off on it. This is the perfect opportunity to jump start Archie’s boxing career. Mad Dog tells Veronica to keep him in mind should she ever decide that she wants another boxer under her roster. Fangs comes running from the back soak and wet. He tells them about a busted pipe, which he shut off, but it needs fixing. Archie volunteers to fix it, but Veronica would rather he call a professional plumber. Speaking of which, as Archie’s manager, Veronica had been thinking about updating the gym. She even offers to front all the money. La Bonne Nuit has been doing well, and she would like to diversify her portfolio with property on the south side.
Mad Dog assists Archie during his workouts in order to help him lose the 6 lbs needed to meet weight. After days of working out, throwing up, and ice baths, Archie just barely makes weight.
Mad Dog and Archie spar at the gym. They break, and Archie tells him about his plans to make changes. He wants to make the gym into a halfway house or community. A place where the kids can go to stay off the streets. And he wants Mad Dog to help him run it.
Mad Dog is shown to be a well built.
The relationship between Archie and Mad Dog first started out rough, with the two barely saying a word to each other. After sharing a prison cell for some time, they became friends, protecting each other. They both eventually found themselves entangled in the underground fight club ran by Warden Norton, who Archie repeatedly disobeyed. Just as they finally came, Archie returned to his cell after the prison yard riot to find Mad Dog was gone. He was told that Mad Dog died during the riot, but Archie knew that to be a lie. Mad Dog later returned to help Archie escape, and in return, Archie blackmailed the Governor to get Mad Dog pardoned from Leopold and Loeb. The two have shown their loyalty and have proven that they're willing to fight for the other.
- "Chapter Thirty-Seven: Fortune and Men's Eyes"
- "Chapter Thirty-Eight: As Above, So Below" (mentioned)
- "Chapter Forty: The Great Escape"
- "Chapter Fifty-Two: The Raid"
- "Chapter Fifty-Three: Jawbreaker"
- "Chapter Fifty-Four: Fear The Reaper"
- "Chapter Fifty-Five: Prom Night"
- "Chapter Fifty-Seven: Survive The Night"
- Unlike most of the other characters, Mad Dog is not a character from the Archie Comics.
- ↑ Murray, Greg & Hasan, Ace (writers) & Romanowsky, Pam (director) (November 14, 2018). "Chapter Forty: The Great Escape". Riverdale. Season 3. Episode 5. The CW.
- ↑ Murray, Greg & Hasan, Ace (writers) & Romanowsky, Pam (director) (March 27, 2019). "Chapter Fifty-Two: The Raid". Riverdale. Season 3. Episode 17. The CW.
- ↑ Paterson, Brian E. & Anderson, Arabella (writers) & Correa, Gabriel (director) (April 17, 2019). "Chapter Fifty-Three: Jawbreaker". Riverdale. Season 3. Episode 18. The CW.
- ↑ Schoenberg, Janine Salinas & Ewing, Will (writers) & La Roche, Alexandra (director) (April 24, 2019). "Chapter Fifty-Four: Fear The Reaper". Riverdale. Season 3. Episode 19. The CW.
- ↑ Lundin, Britta & Turner, Devon (writers) & Katzenberg, David (director) (May 1, 2019). "Chapter Fifty-Five: Prom Night". Riverdale. Season 3. Episode 20. The CW.
- ↑ Aguirre-Sacasa, Roberto & Grassi, Michael (writers) & Talalay, Rachel (director) (May 15, 2019). "Chapter Fifty-Seven: Survive The Night". Riverdale. Season 3. Episode 22. The CW.