vegas

First year:

Sirius' youngest brother's entrance at Hogwarts was sort of the event the Marauders were waiting for since the past year. Sirius wouldn’t stop chattering about it, but he seemed kinda disappointed when Regulus wasn't put in Gryffindor like him, and neither seemed to be willing to meet his new friends.

As Remus and Peter accepted Regulus' refusal of their friendship well, James was a little amused by the youngest Black, with his curly hair and his red cheeks. "How can he be so similar and so different from Sirius?" James thought. And he noticed that the mere glance of Regulus would cause the same sensation in him as Lily’s smile did. Intrigued, he started to notice Regulus, at first just to be sure he was adapting well to the school; after all, he was Sirius' brother. But after a while, he could feel Regulus' presence without even searching for it.

Regulus, on the other hand, felt like his world crashed in front of his young eyes. It was always his dream, his and Sirius', to attend Hogwarts, and they both did it. But his big brother had made new friends who were noisy and annoying. It was a group Regulus knew from the very beginning he would never fit in with, so he pushed them away, despising how much it hurt Sirius' feelings.

Second year:

In their 3rd year at Hogwarts, the Marauders already had made a big reputation, and everyone was always talking about them in the halls. Regulus used to be annoyed about people talking about his brother every time they talked to him, so he approached the only Slytherins who didn't: The Rosiers, Barty and Dorcas.

That, of course, pissed Sirius off so bad that he wouldn't stop complaining for almost a month. And once he was done with it, he had a huge fight with Regulus in front of everyone. Reg was so angry when he shouted, “Well, if you weren’t busy with your new family to remember you already had a brother, I would probably stay with you," that he didn't realize what he did until it was too late.

James was heading straight to the common room with candy to cheer up Sirius when he heard a soft whimper coming from a crying Regulus curled up on the ground like a ball.

"You know, he just wants you to be safe,""He doesn't care about me; he has you now," "That's a lie, Regulus. Sirius might love me, but he lives for you. We shouldn’t make him choose one if he could have both. You don't need to stand by me, just don't hate me... please?"

Third year:

Reg starts to respect James, now knowing he isn't trying to steal his place in Sirius' heart.

Regulus struggled with DADA; James offered to help.

Reggie is convinced by the very stubborn Marauders to accept his help.

They fought a lot at the beginning, always arguing about anything until James found that if he teased the right nerve, Regulus would blush and forget his words.

James found a new pleasure in life called making Regulus Black laugh or blush.

They start to get along; Regulus is understanding DADA and got his first high grade with James' help.

But James is really confused by the way he is feeling about Lily and Regulus.

James works out that Lily will probably not give him a chance anytime soon, and Regulus' heart does a backflip when he hears it.

They start to hang out even outside of the study section, sitting by the Black Lake where no one can see them, just to chat about literally anything. And Regulus is impressed by how smart James Potter actually is behind the flirty smile.