Grian

Appearance
Grian is a sandy-brown haired brit with black eyes and pale skin. In Yandere High School, he has quite a few outfits. The first was a white tank top with red swimming trunks and an obvious spray-on tan that he wore to the beach in his debut episodes (episodes 45, 46, 47, and 48). His usual outfit after his debut is a red sweater with the sleeves folded up to his elbows and dark gray, almost black, jeans and black shoes.

When Taurtis was hospitalized because of a stab wound, Sam forced Grian to wear Taurtis's clothes, claiming that it would help him cope with the absence of his friend. Taurtis's clothes consisted of a blue t-shirt with a big letter T on the back with a white collar and black suspenders, along with black jeans, red and blue headphones, and red and blue sweatbands.

In Tokyo Soul, Grian often wears the school uniform which consists of a light blue blazer, a white button up, black dress pants, black shoes, and a black tie.

Personality
Grian is a very blunt person, but is also considerate and kind when he first appears in the series. He listened to Sam and did as he asked in the beginning, but as time progressed, Grian quickly recognized that listening to Sam blindly wasn't very wise. As the series progresses, Grian becomes more comfortable with killing and participating in illegal activities, especially in Tokyo Soul. He has killed quite a few people, including the Yakuza's leader, Karu, several innocent civilians while robbing a store, Aphmau, and others.

Despite this, he is the most reasonable person in the danger trio, and is easily the most intelligent. Grian easily recognizes when something is wrong or when something is a bad idea, unlike Sam and Taurtis, who are rather gullible and dense.

Grian is known to show a soft spot to people he care about, like Silly and Ellen, and he often shows closer attention to those people, as well as try and strike up small talk with them.

Grian is shown at times to be quite scared of Sam and Yuki as well, especially during Sam's delusions of Grian being Taurtis after Taurtis was hospitalized due to stab wounds. after being threatened and forced by the pair to be Taurtis, Grian claims to hate Sam, but if this is true he never acts on it, even when given the opportunity to get away from Taurtis and Sam by being sent to the wrong Tokyo, being sent to Canada instead. he instead spends all his money to get a flight to Tokyo, Japan to get back to them, which is odd behavior for someone who hates their friends and was given the chance to get away from them.

Sam
Sam and Grian's relationship is complicated. They were friends back in elementary school when Sam was five and Grian was seven, and call each other their close friend, but Sam is very unkind to Grian, berating him and blaming him for everything that could be considered bad, which is a form of gaslighting. Sam also forced Grian to wear Taurtis's clothes and pretend to be Taurtis during his absence, something that Grian doesn't let up, even in Tokyo Soul. They get along in Tokyo Soul, but there are moments (like in the first Star Wars episode) when they rub each other the wrong way. In that episode, it was revealed that the reason that Grian was absent in the past few episodes because Sam dressed him up like Princess Leia and locked him in a secret room in the basement for three days. This relationship isn't very healthy, not just considering the fact that Sam berates and traumatizes Grian, but also considering that Grian has said that he thinks that Sam is "the worst person alive" (episode 21.1) and was clearly scared of Sam in Yandere High School (episode 51, 52, and 53).

Taurtis
Taurtis and Grian are also childhood friends, becoming friends when Taurtis was five and Grian was seven. They seem to be on better terms than Grian is with Sam, despite Grian dressing up as Taurtis and pretending to be him. They both seem suspicious of Sam in Tokyo Soul, and are also scared of him. A lot of references that Grian and Taurtis are closer than most friends are made in Tokyo Soul as well, such as them joking about "Glarging" each other (episode 47) without any explanation to what "Glarging" may be, as well as them arguing and Taurtis asking "Why can't we be like the other couples?" (episode 48). However, all of this could be them joking around.

Ellen
In Yandere High School, Grian was matched with Ellen by Sam in the Halloween episodes and started dating. However, their relationship became complicated when Grian had to pretend to be Taurtis, and they broke up after Grian and Pielord had a knife fight over them. It is implied that they still have mutual feelings for each other, but Ellen believes that it's too dangerous from them to date Grian during the events of Yandere High School.

Silly
For most of the first season, Grian and Silly don't talk much but appear to be on good terms. However, towards the end of Tokyo Soul Grian takes Silly on a date, where they use the labels boyfriend and girlfriend. Other than that, they don't have much of a relationship on screen.

Trivia

 * Grian has said in Tokyo Soul that he likes beards, especially stubbles and peach fuzz
 * He also may be pansexual, as he says that he is uncertain what he's into after his time with Ellen
 * Grian is the oldest student, as in Japan he is two grades below
 * While undercover, Grian's name is Charles, which is ironic as that is the actor's real name
 * In Yandere, Grian mentions that his parent's are divorced
 * In Yandere, Grian mentions that if someone called his parents, it would go straight to the butler, implying that Grian's family is rich