Calm before storm.
Regulus found out 2 weeks later from hearing James and Remus talk that Sirius did not infact drink happily. He drank to forget, he felt like shit for thinking that lowly of his brother.
He did not expect James Potter to stop him and ask to talk privatly though. He had a feeling it was about Sirius, and his gut told him to accept it. But his mind told him to brush him off and go back to his dorm, he was conflicted.
He wanted to know about his brother, but his brother didn't even care, right? He didn't know anymore. He brushed him off and went back to his dorm, he regrets it.
He does a lot of things he regrets.
A month after James tried to talk to him, James tried to talk to him again, Regulus brushed him off. But there was a difference now, the difference was his brother was being a complete ass to him.
Maybe it was his fault but it was because of his idiot brother.
They went home for Christmas, Regulus tried to ignore the way he saw Sirius completely ditch him once they got on the train.
When he came back, he soon learned Sirius was spiraling. James didn't notice much, but Remus did. And Remus found him in the library again to tell him. Regulus didn't know what to do with this information but he didn't want his brother to be like this, so he stopped giving him the cold shoulder.
He didn't avoid him, he didn't glare at him. But he was still fairly pissed at Sirius, he still loved him though.
So one night when he was going to the Astronomy tower, he noticed Sirius was already there. He internally groaned, but kept a straight face as he walked over and stood next to his brother to look at the stars. Refusing to look at Sirius was the only way he wouldn't break.
He wanted to reconcile with Sirius, he can admit he said some fucked up shit, but so has Sirius.
"I'm sorry" Sirius said quietly. Regulus was surprised, he didn't actually expect him to say anything or even say sorry. Sirius does not say sorrylightly or ever.
"I should have been a better brother" Sirius said.
Regulus felt his heart ache, his heart aches because he knew Sirius was the best brother ever. And Regulus has treated him like trash for 3 years, Merlin did he feel guilty.
"You are the best brother" Regulus whispered. He was surprised when Sirius turned to face him, Sirius turned Regulus to face him, before fixing a few strands of his hair.
...
Little 9 year old Regulus was hella nervous as he quietly knocked on his older brothers door, a muffled 'come in Reggie' came from the other side.
Regulus held back a smile as he stepped inside quietly and closed the door with a soft click, Sirius knew it was him just by his knock.
"Siri? Can you do my hair like yours?" Little 9 year old Regulus hesitantly asked. 10 year old Sirius smiled softly, "Of course Reggie, come here" Sirius said and patted the spot on his bed in front of him.
And that's how they spent their day, doing hair, Sirius even let Regulus braid his hair. It was a good day.
...
Regulus wanted to cry, he didn't until he got back to his dorm.
...
Sirius wanted to sob his heart out, he did after Regulus left.
...
It's not like Sirius and Regulus would talk every day after that, but they didn't avoid each other. Sirius would stop Regulus in the hall and fix his hair, Regulus would let him. Regulus would see him in the Infirmary when his stupid friend James told him Sirius got in another fight. But they had more of a connection the next 5 months then in the last 3 years.
Sirius really was spiraling, and everyone could tell. It wasn't life threatening, but he got in fights, he drank more, he skipped classes, it wasn't good. Father and Mother surely wouldn't like this.
...
Sirius knew it was getting bad, he got more reckless and irrational, but how could any of it get worse. Merlin he jinx's himself.
...
One night when they both ended up in the astronomy tower, Regulus decided it sould be fun to tease him. "So James Potter huh?" Regulus said. Regulus knew, bloody hell everyone but James knew Sirius was smitten for James.
"Shut it Reggie" Well Sirius shut that down pretty quickly. "What? It's not like i can't tell" Regulus replied. "He likes Lily Evans so it doesn't matter." Sirius said. Oh, sore topic, whoopsies.
"Oh, sorry" Regulus said, suddenly feeling a bit bad for bringing it up. "It's fine" Sirius said with a sigh. It wasn't but Sirius was good at hiding that fact.
...