Cub spends most of his time with Pop in almost every episode he appears in, so he doesn't interact with many characters outside of his dad. He hardly ever interacts with anyone, even in the episodes in which he appears without Pop. However, when he does interact with the other characters, he usually has a very stable and positive relationship with them.
In Cubtron Z, Cubtron uses Giggles as a crayon. In Kitchen Kringle, Cub and Giggles are going to eat dinner in the same house. They are both invited to the same birthday in I Get a Trick Out of You. Cub also annoys Giggles in Wingin' It when he hits the back of her chair with his toy plane.Rink Hijinks and Just Desert. He also cosplayed as an early version of Lumpy in Wrath of Con and was suppose to eat dinner with him in Kringle Feast.
This is another character that Cub appears to be friends with, on his side. In Hello Dolly, Cub waves at Petunia as she walks by and in You're Kraken Me Up, he appears to be very interested in her head.
One of their interactions together is in Don't Yank My Chain, when Handy is being dragged to death by a train while Cub laughs and waves at him until Handy is dead. Handy also babysits Cub in A Handy Nanny. Coincidentally, Cub laughs at Handy's pain in that episode as well.
Nutty is most likely the only character that Cub dislikes. In A Sucker for Love Part 1, Nutty swipes a lollipop that Pop gave him, causing him to cry. This may have changed now in the future either because of the lack of continuity or that he is easily forgiving (similar to how he forgives Pop on many occasions in spite of the torture he receives from his poor parenting skills). However because there is no concrete evidence supporting this, it is safe to assume the latter is more likely.
Cub has never directly interacted with Sniffles, but he did see Sniffles die in Who's to Flame? and was awed by his fire hat.
- Main article: Pop-Cub Relationship
Being father and son, Pop and Cub clearly love each other like a family should, and they're always seen together when they both appear in the same episode, seen having a relationship with each other.
Despite the pain Pop frequently puts on Cub, Cub still loves him back, though this may be because of the lack of continuity or because Cub is too young to have feelings of hate or distrust.
In A Sucker for Love Part 2, Cub is given a lollipop by The Mole in order to get him to stop whimpering. Though this scares him because of the face his skin makes. Cub plays with The Mole's remains in Spare Tire, though this may be because Cub was too innocent too understand death and thus didn't realize that indeed he was playing with The Mole's corpse.
There closest interaction is in A Vicious Cycle. Cub has absolutely no reaction to Disco Bear's death and stares at his mutilated head with no expression. Just like many other examples, this may be because Cub is to young to understand death.
Cub may be the only character to be friends, or at least on neutral terms, with Fliqpy. In A Vicious Cycle, Fliqpy pushes Cub off his tricycle to use it as a weapon but makes no attempt to kill him. When he is a bike and has killed everyone in the house, instead of looking for more characters to kill he actually lets Cub ride him around. However, he may have killed Cub offscreen or it may have been "good" Flippy (Debatable). However, Fliqpy does kill Cub in Flippin' Burgers, but this was most likely unintentional.
Cub, like most characters, is a fan of Splendid. He goes to his convention in Wrath of Con and he waves to him See What Develops. However, since Splendid was wearing a disguise, Cub might have thought he was waving to a stranger.
- Cub has yet to interact with Flaky, Russell, Mime, Cro-Marmot, Lammy, Mr. Pickels, and Good Flippy.