Cater is patient with Grim during Beanfest despite how Grim keeps wasting their limited ammunition, teasing him by sneaking up behind him during the event. Grim, Cater and Jade all take a photo together at the end.
Grim has a voice line about sticking close to Cater in order to get Idia to leave him alone.
In a rather uncharacteristic move for Grim, he gifts Trey with a can of tuna as a get-well present after Trey is injured in Book 2.
Trey has a line about getting a toy (presumably for cats) to help Grim keep his teeth clean, and he feeds both Grim and the prefect during Vargas Camp.
In another line Trey cautions the prefect against wandering around alone, as “somebody has to keep an eye on Grim, you know.”
Trey helps look out for Grim during the Firelit Sky event, cautioning him about falling into a canal (which Grim then does) and scolding him afterwards.
He also rescues Grim after he gets himself trapped in a vase.
During the Vargas-monster attack of Vargas Camp 2 Trey protects both Grim and the prefect by having them hide behind them as he deflects stones that the monster hurls at them.
Like most people, Grim mistakes Epel for a girl when seeing him for the first time (“The girl with the potion books, I really like her!”)
Much like Epel, Grim prefers to be called “cool” rather than “cute.”
When Epel invites Grim to participate in the Harveston sled race, Grim refuses, saying that he will go on the trip to eat apples but he “ain’t messin’ with no sleds.”
Grim assures Epel’s grandmother that he is “always cleanin’ up Epel’s messes on campus” but Epel responds, “I can’t think of a single time you’ve done that.”
Twisted Wonderland Reference Note 