@eunoiastarz and I were thinking about how the one, the only Garth Fitzgerald IV would fit into bloodboyfriends <33
Garth enrolled at Stanford with his highschool sweetheart Bess to study child psychology, which is how he ends up rooming with fellow child psych student Castiel. The two (well, three <3) hit it off and become besties right away. They find comfort in finding people just as genuine as they are in a world where people are so hard to understand. Alongside Anna (well, the demon possessing Anna unbeknownst to Cas...), Garth and Bess are the first friends Cas makes when he finally gets out of the MoL cult.
One day while on the road with Balthazar and Gabriel, Cas gets a call from Bess, who tells him that Garth has gone missing. The three of them head back to Stanford, as much to use their tracking skills from hunting to figure out what happened to Garth as to comfort Bess. The three of them end up finding out that Garth was turned into a werewolf and went into hiding. While Cas and Gabe slip back into the anti-monster ideals tortured into them since childhood in the cult, Balthazar does something different-- he saves Garth. Balthazar was forced to change species against his will; he knows firsthand what it’s like and that being a “monster” doesn’t necessarily make you evil. He convinces Cas and Gabe to stand down (harder than you’d think, because even if neither of them want to kill Garth, their training in the cult is hard to overcome).
Garth gets his happy ending, of course. He doesn’t become a hunter, rather he learns how to live in his new situation while going back to finish school and continue building a life with Bess. The boys work cases for him when Garth brings them to their attention.
And now for the specifics :)
Garth and Castiel study and work on psych projects together. They made sock puppets, including Mr Fizzles, together for one of these projects, and Garth keeps all of them.
However, only a small amount of studying is actually done during their study sessions. Most of these sessions are spent gushing about their loved ones-- and about all the school gossip. Garth and Cas are pretty quiet, the kind of quiet that makes others forget they’re there at all, so the more popular kids will gossip in front of them without even thinking about it (plus, Garth and Cas are always open and upfront once you start talking to them; they just have those faces and personalities that make you want to open up and say everything to them, and people will start saying things they should really keep to themselves before they know they’re doing it)
Because they know literally everything that goes on in school, they’re the first people Bal turns to when he needs blackmail material against those who annoy him. After leaving Stanford, Cas tells Gabriel the stories he’s lived and heard on long car rides. Gabe ends up finding himself remembering names and coherent lives of these random people cas never even interacted with— he tells Cas he’s like a podcast.
Garth ends up teaching Cas how to dance for Balthazar <3 Cas and Bal still end up tripping over each other’s feet the whole time tho
Bess helped pick Castiel’s outfit for his and Bal’s first date, and is sure to include Cas’ trench coat because the battered old thing is comforting to him
Garth is one of the first people to show him any affection after he left Anael behind in the MoL cult; Garth hugs him and when cas just starts randomly crying he’s SO concerned he did something wrong but cas just hugs him tighter
Cas still isn’t sure he’s worthy of any kindness after the way he was treated in the cult (would it have even happened to him if he hadn’t deserved it? No, he reminds himself, because Anael went through the same-- worse, actually, and she never deserved it for a second) and leaving Anael behind, but Garth and Bess help him with this so much
Snips ends up being afraid of Garth after he turns into a werewolf, even though, just like Balthazar, they were really close before. Garth doesn’t hold it against Snips, of course, but Gabriel makes a joke about how cats and dogs don’t get along and Bal and Cas hit him upside the head.
Also I think Garth and Bess would be really overprotective of Cas. They’d know from how little information about American society Cas has, his less than stellar social skills, and his apparent lack of a past that there’s something... not quite right. They don’t know what it is and don’t want to speculate, but... they know it’s bad. Garth couldn’t tell you how many times he’s been woken up at night by Cas screaming or whimpering in his sleep, he’s seen the scars on Cas’ skin occasionally in the moments where Cas doesn’t pull on clothing fast enough, scars that Garth has no earthly idea how to tell what the causes were because he’s seen nothing like them. They’ve heard Cas mutter names of people they don’t know when Cas thinks no one can hear, alongside things like “i’m sorry,” and “if only you were here too.” It practically killed them when Cas disappeared right after Balthazar died. Cas had gotten rid of his phone entirely, hoping (with Gabe’s encouragment-- at first, at least) that if he cut everyone from Stanford off entirely, leaving them behind wouldn’t hurt as much, because he’d forget them and how much he loves them, and they wouldn’t remind him of Balthazar. But eventually Cas gets taken in by the police because Garth and Bess filed him as a missing person, and that’s when Cas gets a new phone and assures them that he’s okay, he’s just... leaving for a bit. Needs to clear his head after everything that happened. The three of them stay in contact after that, but never more so than after Garth gets turned and Cas tells them everything (well, mostly everything) about the things he’s experienced in his lifetime.