Regulus walked out of his last class of the day, which had been Transfiguration. He had stared out the window for the majority of the class wishing he could be out in the sun. It was probably one of the last sunny days they would have for a while, seeing as winter was just around the corner, and the snow could come any day now.
Now that he was done with his classes for the day, he could go out and enjoy the sunshine. He walked down the stairs and into the Entrance Hall. He walked outside, and despite the cold air, he didn't let it stop him from enjoying the day. He sat down near the Black Lake. He wondered how the Black Lake had gotten its name. Maybe that would be a question for his grandparents.
Regulus opened one of the books he had taken from the library, one on magical creatures. Hagrid had recommended this book to him after Regulus had asked if there was a book he could read that went into more detail about the creatures they were learning about.
Regulus was hoping for a quiet afternoon of relaxation, but it was not meant to be. Regulus heard footsteps approaching. He looked up only to see Peter Pettigrew walking his way.
"Hey, Black," Peter greeted coolly.
"Pettigrew," Regulus greeted him in the same tone. Clearly, he wasn't the only one enjoying the outdoors today. "Do you need something?"
"No," Peter responded. "But you are sitting in my spot."
"Excuse me, but what are you talking about?" Regulus asked. "I was here first. And anyway, there are so many places to sit around this lake. I'm sure you can sit somewhere else around the lake." Regulus definitely noticed that this Peter Pettigrew was very different from the Peter Pettigrew Sirius had mentioned from the original timeline. The Peter from that timeline had been more like a follower, someone who was quiet. This Peter was not like that at all.
"Move, Black," Peter commanded.
"Hey, don't tell me what to do!" Regulus snapped.
"Do you know how to swim?" Peter asked.
Regulus frowned at his question. "Why do you ask?" he asked suspiciously.
"Oh, no reason. I'm just wondering," Peter said quickly, a little too quickly.
Regulus snorted. "Don't try that with me," he stated. "I know how Slytherins work. Members of my family are largely from Slytherin. Slytherins never ask a question just because they're wondering. Nice try, Pettigrew. Now, why are you asking this question?"
Peter came closer. "Get lost, Black," he said coldly. Regulus made a mental note to tell Sirius about this not very shy Peter Pettigrew later. Clearly, Slytherin had shown his true intentions early on. He was sure that they'd be analyzing this later.
Regulus stood quickly. "What are you going to do?" Regulus asked, not liking the glint in Peter's eye. Peter reached out, and shoved Regulus to the side. Regulus nearly fell into the lake, but he caught himself just in time.
"Maybe you should go for a swim," Peter said casually, as if he was talking about the weather. Before Regulus could react, and before Peter could try shoving Regulus into the water like Regulus knew he was probably going to do, there was a bark, and quick footsteps.
Regulus widened his eyes as he saw Padfoot dashing their way. Sure, he had seen Sirius transform during their lessons, but this was the first time Sirius had transformed outside of lessons.
Padfoot sprung forward. "Padfoot! No!" Regulus yelled, but it was too late. Padfoot sprang at Peter, knocking him into the lake. Regulus glared at the dog, and immediately helped a spluttering Peter out of the lake. Thankfully, it had been the shallow end, so no drowning occurred, but just the same, Peter was coughing up water.
Padfoot turned back into Sirius. "That's what you get for being a git to my brother!" Sirius spat.
Peter's mouth dropped open. "Y-you're a…" he trailed off.
"Yes, yes, and I bet you would be a rat if you had an animagus form," Sirius commented. "You're nothing more than a…"
Regulus knew that Sirius did not know how to control his temper around Peter, so he needed to interfere before things got worse than they already were. "Sirius, come on. Leave him be. He's not worth it," Regulus interrupted his brother's rant. He took Sirius' hand and dragged him away from Peter and back towards the castle.
"Regulus, I…" Sirius started but Regulus interrupted.
"Sirius," he began, then paused to make sure that Peter was no longer within earshot. "Look, I know you hate Pettigrew, and honestly, he's a big git, even now, but despite all this, well, you shouldn't lose your temper, you know?" Regulus hoped Sirius would get the hint.
"Alright, fine," Sirius muttered. They walked into the castle and headed back to Gryffindor Tower.
"Remember, Sirius, you're not a child, literally," Regulus reminded him.
"I know, but every time I see him, I can't keep it together," Sirius said bitterly.
"Hate to break it to you, Siri, but I think you've already been caught," Regulus said, seeing their grandmother heading their way.
"Sirius Orion Black!" Melania scolded as soon as she got close enough. "What do you think you were doing, pushing a student into the water like that? If it had been deeper water, he could have drowned!"
"You don't need to lecture me, Grandmother," Sirius snapped. "I'm not a child!"
Melania took a deep breath before saying, "Come with me, both of you."
Sirius and Regulus followed her to Arcturus' office. Melania spoke quietly with him for a moment, most likely telling him what had happened. Finally, they both turned to Sirius and Regulus.
"Regulus, can you please tell us what happened from your perspective?" Arcturus asked. Regulus recounted what had happened from the moment he had gotten to the lake all the way to when they headed back into the school.
"Sirius, can you tell us what happened from your perspective?" Melania asked.
Sirius decided to be honest. He recounted what had happened. He then added, "Not surprised he went tattling on me immediately."
"Sirius, you know better than this," Arcturus said sternly. "You are old enough to know that what you did was wrong. It does not matter who it is. You should never push someone into the lake, whether or not it's deep."
"I'm not a child!" Sirius snapped.
"Perhaps not, but what you did today was childish," Melania stated. "You really need to control that temper of yours."
"And I know you know how to do so, because we've done Occlumency lessons," Arcturus said.
Sirius nodded. "I know," he admitted. "I… I guess you're right. I just wanted to help Regulus."
"And in doing so, you did the same thing that Mr. Pettigrew was going to do," Melania reminded him. "Think before you act, Sirius. You don't want anyone drowning, do you?"
"No. Sorry," Sirius apologized.
Twenty-five points were taken from Gryffindor, and Sirius was given detention for a month. He was also given a stern warning about more severe consequences if something like this ever happened again.
As they left the room, Regulus grinned at Sirius. "You are right about one thing though. He would be a rat!" For the first time since being caught, Sirius burst out laughing.
"Yeah, he's a rat alright," he replied with a grin.
"And hey, Padfoot is back!" Regulus exclaimed, clapping Sirius on the shoulder.
With that, Sirius turned into Padfoot, and chased Regulus as he ran back to Gryffindor Tower.