
Please be informed that I will share the summary of volume 3 (continuation of Ren's brother's story)
Where should I start, his older brother, Saotome, is probably one of my most favorite character in the whole series along with Jinguuji.
Let's start with Jinguuji. He was a son of a neglectful mother who was also a prostitute. She would bring men everyday and once she brought a man who attempted to SA the kid Jinguuji but his teacher managed to be near his house and heard him scream for help. The female teacher saw little Jinguuji was stabbed on his left abdomen by the man so she decided then and there that she would help him. She became his adoptive mother. The scar from the stabbing was then covered by tattoos as seen when Jinguuji was older. His teacher was also the one who found out that Jinguuji is a genius from a young age.
Saotome on the other hand, like mentioned here, had been living in so much pressure from his parents and family's expectations.
Continuing after their story in volume 2, Jinguuji continued to tutor Saotome in exchange for seggs. However both of them had inevitably become much closer each time they spend with each other.
Many things happened but the climax was Jinguuji fell and almost died because a man hated him and decided to unalive himself with Jinguuji by jumping over an overpass. Saotome was so heartbroken and it was then he decided to cut ties with his family for good. Jinguuji woke up from his coma. There's this amusing thing that happened but I'll leave it since it's much better to read the accurate transition in the manga than me summarizing it.
Anyways, in the end Saotome and Jinguuji end up together and both are very successful doctors, with Jinguuji being a neurosurgeon. Saotome also met Ren and his lover in an extra chapter and it was so funny how they just couldn't believe Jinguuji was a neurosurgeon because of how he looks (Jinguuji really never changed his style, he's so grounded and I can see how Saitome was so inlove with him, he's this solid rock he really needed and deserve), they were thinking he was probably with the mafia because of all his tattoos lmao

And I just know Garam has a sad back story. With the way he struggles to pay for his tuition and his very desire to be always on top. Did his family cut their ties with him because of his orientation? I am so so curious. There's got to be something sad that happened in his past.

Spoilers
Until what chapter of the raws have you read because chapter 40 showed a little back story.
The raws suggest he at least contacts his mom because he said he didn't want to tell her if he decides to work part-time. I think rather than cutting ties, it is also possible that he doesn't want to burden her after what happened in the past.

I read the raws and all I can say is the ML is a hot mess lol he doesn't know what he wants, he denies he has feelings for Garam but is thoroughly bothered when Garam acted like nothing happened and is so annoyed when Garam wants to stop having the fubu thing with him because guess what, Garam my baby is catching feelings nooooo, now we wait on how things pan out for them.
I am rooting for Garam all the way, nothing is impossible with his lol
Taiga is one precious man.