Big Roommates 2 is the third episode of Big Hero 6. It premiered on June 9, 2018.
It is Mystery Loaf Monday at the school cafeteria, and Fred has helped himself to some mystery loaf. His friends are not so keen about him having mystery loaf for lunch, especially since they have no idea what is in it. Honey Lemon is also reloading her chem-purse at the table when Wasabi rushes over, relieved that she is alright for some reason. Honey had an accident while trying out a new formula for instant ice. She ended up freezing her entire apartment and her roommate. So, until her apartment thaws Honey needs to find a new place to live. She decides to stay with Go Go, despite being told that where she lives is a sketchy neighbourhood. Go Go eventually welcomes her to stay after Honey persuades her. Everyone helps Honey move her stuff into Go Go's apartment, which is in a rough part of town. Despite Go Go's warnings about the neighbourhood, Honey's positive attitude makes her careless when she leaves her chem-purse unsupervised. A down on his luck thief named Dibs steals Honey's chem-purse, and takes it to a warehouse which happens to be a secret lab belonging to Alistair Krei. Hiding, Krei reveals that he has invented and new improved version of Hiro's neurotransmitter for the Microbots. Krei's rip-off can control anything linked to it with the mind. Overhearing that it is worth a fortune, Dibs decides to steal it for himself. When Krei leaves the warehouse, Dibs tries on the neurotransmitter, but accidentally breaks Honey's chem-purse. Purple goo bursts out and consumes Dibs, turning him into a gooey monster.
Meanwhile, both Honey and Go Go have a hard time living together. Honey fills the apartment with butterflies, and places cute stickers all over Go Go's refrigerator and food. Go Go does her sparring while Honey tries to do her yoga, and accidentally slices her roses while doing target practice with her disks. Honey eventually realises that her chem-purse has gone missing. Go Go says it was probably stolen, but Honey, being optimistic as usual, does not think so. She is confident that it will show up. At the Lucky Cat Café, Fred charges in with news that a monster is loose in the city. His friends tell him that monsters are not real, but Fred as usual convinces everyone to check it out. Go Go meanwhile is fast asleep after being kept awake by Honey's snoring. Hiro and Fred are out on the streets searching for clues, and find a goo sample that was left by the monster. Go Go later wakes up back at her apartment in Baymax's arms. Wasabi is trying to find Honey's chem-purse, and Go Go again says it was stolen. Honey is still being optimistic that it will show up, and soon an argument breaks out between the two. Just then, they hear screaming coming from outside. It is the monster.
The monster is actually Dibs, and is confronted by Wasabi, Baymax, Honey, and Go Go. According to Baymax, the chemicals covering his entire body is being control by the neurotransmitter he is wearing. Realising it was her purse that turned him into a monster, Honey becomes ashamed and disappointed. Go Go was right and she did not listen. The team tries to catch Dibs, calling him "Globby", but he gets away when he accidentally gets run over by a bus. At Go Go's apartment, Hiro builds honey a new chem-purse. Honey no longer feels like the bright and cheerful girl she usually is. She has now become a more serious person facing the darkness of reality.
Meanwhile, Globby kidnaps Krei so he can find out more about the neurotransmitter and how to control it. He takes him to the top of a skyscraper. Big Hero 6 come to his rescue, and Wasabi engages Globby in a fight. However, he soon chickens out when his fear of heights gets the better of him. Globby becomes very frustrated, and threatens to throw Krei off the building. The team sees that he needs positive reassurance, but Honey does not feel she can help. Go Go is able to convince by being sorry for criticising her optimism. Even though she finds her ridiculous upbeat attitude annoying, she would not want her to change that for anything. After reconciling, Honey gives Globby a pep talk. She manages to get through to him that while things have never worked out for him before he could consider this a new beginning for himself. After he lets Krei go, he tries to take back the neurotransmitter, but falls off the building. However, Globby saves him. He is grateful for Honey believing in her, and, much to everyone's shock, decides to become a super-villain. He steals Krei's wallet and escapes, embracing his new identity as Globby.
- The US premiere date for this episode was leaked for March 8, 2018, but Bob Schooley confirmed that this announcement was not the official premiere date.
- When Honey Lemon pops Go Go's bubblegum, her fork changes into a knife and then back to a fork.