Regulus Black would be the first to acknowledge that he has not had many best or good days in his life. Maybe it was because of the family he was born into, the people he associated with, or truly his life choices. His relatively short life had clear distinctions before Hogwarts and after James Potter. After all, there wasn't much after Hogwarts. In terms of the number of best days, he could think of some, but only a few.
Before Hogwarts, it was him and Sirius against the world. Over whispers, they would plan their escape from 12 Grimmauld Place. Of course, that would never happen, but one can hope, be brave, and live in delusions. There were some fun activities. For example, they even would convince Kreacher to join in on some of the pranks and games that they would play. Sirius would take the fall for the pranks. Or sometimes, it was forcing Kreacher and Sirius into making mud dishes, a version of potions, but not real potions because they were kids, nor did they have a genuine Potions kit. They would find random "ingredients" and sometimes send Kreacher into the dangerous Muggle world to find peculiar ingredients. Other times, it was sneaking outside into the little garden and finding the snitch. Regulus loved diving for the snitch. He never crashed into the garden or the pavement. Sirius even complimented his skills; he was called a natural, a future Hogwarts and professional Seeker.
However, eventually, Regulus stopped joining his brother in these pranks and rule-breaking. Sooner rather than later, Grimmauld Place became even quieter. Walburga and Orion disliked the rule-breaking. They had Sirius, the heir, and Regulus, the spare. They were a part of the Noble and Most Ancient House of Black; they must act like dignified members of the wizarding world, not like children.
Regulus dreaded Sirius' Hogwarts acceptance letter. He was more of a pessimist, so something good would happen for him once he himself received his letter. His parents would then focus entirely on him. Of course, he was a little jealous since Sirius could leave; he could escape sooner than Regulus. But they made plans; both would escape.
James Potter. The unmentioned name in the Black family. Never mind that he was a distant relation of one of their cousins or great aunts. It soon became "Potter and I," "James this," "James that," and slowly, Regulus realized that he was about to be replaced. It was no longer Regulus and Sirius Black. Well, it had yet to happen, but who would want to stay associated with Regulus and their parents? It would soon become Sirius Black and James Potter, thick as thieves, practically brothers.
One year later, Regulus Black received his Hogwarts letter. He was sorted into Slytherin. He remembered the first time he met James Potter on the train. It was one of the best and worst days.
Regulus had just entered the Hogwarts Express. He was herded by Sirius to join Sirius' friends even though mother and father told him to sit with the other scions of ancient houses. But Regulus loved his brother because Regulus still saw Sirius as his brother. What would a little difference in Hogwarts House mean? It's just a house; it's not his entire life. Honestly, his mother knows families where their children get sorted into Ravenclaw; however, they rarely get sorted into Gryffindor or Hufflepuff.
It turns out that being sorted in Slytherin and having a sibling in Gryffindor is a big deal. It didn't help that he was a Black, and many fellow Slytherin students looked up to Regulus. Life continued. He started growing up. In fact, everyone started to grow up.
James Potter began to add himself to Regulus' daily life—Potter here, Potter there. Potter—James almost became unmanageable during the fifth and sixth years.
Eventually, Potter became known affectionately as James. Regulus hadn't felt this much happiness in years. He was almost reminded of when he and Sirius were younger when they would play together and create havoc in Grimmauld Place. It felt nice to be around James. Regulus felt like he had some control over his life while the political tensions in the world increased. Of course, James also annoyed him in certain parts, but he knew that James brought out the best in Regulus, and Regulus also enjoyed the warm feeling whenever he was near James.
Prefect rounds, astronomy tower, quidditch locker rooms, quidditch pitch, broomsticks, and going to the Hogwarts kitchen. Those were some of the best days and moments for Regulus Black.
They kept their relationship a secret from the entire world and his friends, and everything seemed perfect. Maybe his friends learned about James, but Sirius never openly noticed.
Despite being a muggle thing, Regulus wished upon every star that nothing in his life would change and that it could stay this simple. However, Regulus has never been particularly lucky. Life was never simple, but he also realized that everything that he has currently is someday gonna be gone.
Growing up was a privilege, but it also sucked.
Orion and Walburga had high standards and demands. Life started to fall apart faster and faster. It was all too fast to stop.
Sirius Black truly did love and still loves his brother James Potter. In fact, Sirius had two brothers. One he wished had never grown up and the other had never gotten to grow up. Well, to be honest, neither had the time to grow up, a wizarding war complicates life.
Childhood at 12 Grimmauld Place was far from ideal. Too many dark and depressing corridors in the house. Too many curses and cursed objects. One unsettling creepy house-elf that would spy on Sirius. However, one ongoing bright part of life at number 12 was his younger brother, Regulus.
Regulus or fondly known as Reggie. His younger brother. The reason why he didn't want to leave for Hogwarts because it meant that Reggie would have all their parents' attention on him. Orion and Walburga may have legally and biologically been his parents, but he much preferred Fleamont and Euphemia Potter as his parents. He wanted to bring Reggie when he left, but he stayed, he chose his side.
Sirius remembers when he finally understood that he had a younger brother that would, well should, have stayed in his life for far longer than he did. Reggie was quiet but a curious sibling. Well, Sirius had never had a sibling before but he saw how Bella, Andy, and Cissy interacted. Interesting.
He had promised Reggie that he would stay with him forever. Forever is a long time for wizards as they can live longer than muggles.
Reggie was afraid of storms—any type of storm, to be honest. If it rained or thundered heavily, he would run into Sirius' room since Sirius was better at comforting him than Orion and Walburga.
Sirius was sure Reggie would deny it if questioned, but Reggie would jump in Sirius' bed, and the two would comfort one another while the storm or disgruntled weather continued.
"I hate the storms and the noise. They remind me of when father and mother are angry at us or someone else. I can't wait until Hogwarts and after Hogwarts," Reggie mumbles between the sound of thunder. He's entirely under the duvet and has all Sirius' pillows. Sirius doesn't have many, but any number of them would help comfort Reggie.
Sirius tries his best to comfort Reggie by tucking him in and attempting some purposeful accidental magic, a basic lumos, since Reggie loves the light, like the sun.
"Reggie, it's just another few years, and then we'll be in Hogwarts together and only have to see our parents a few times during the year. Together, we'll be unstoppable. Then, after Hogwarts, we'll move out."
Eventually, Reggie falls asleep. It's the usual pattern when it storms, and Sirius rarely gets tired of having a sibling interruption.
"Don't you ever grow up, Reggie, just stay this little. I'll protect you so it can stay this simple. I won't let nobody hurt you. Won't let no one break your heart and even though you want to, please try to never grow up. I love you," whispered Sirius.
For much of his childhood, Sirius' best days were surrounded by Reggie. He got along with his cousin Andy until she was blasted off of the family, quite a traumatic event for everyone.
Then, he met James Potter. James was like the sun, intoxicating and addicting. Sirius had good and best days with Regulus, but these days with James were lighter, and Sirius felt better. James showed and taught him that his childhood was messed up and not ideal. He knew immediately that this was his and Reggie's exit ticket. He just had to convince his slightly stubborn sibling.
For Sirius, James was his best day if he wanted the future that Reggie and he had dreamt about during their childhood.
The world would stop spinning if James Potter ceased to exist. James was considered a miracle child in every way possible. Fleamont and Euphemia Potter were thrilled when James entered the world. He was their miracle child. He was also quite spoiled. Practically every day was the best day.
He grew up in a pretty house, Potter Manor. It was a bit larger than just a house, with many rooms, as it was a manor of a noble wizarding family.
One of his best days was when he was five years old during autumn, almost Samhain, Halloween, or All Saints' Day, when the leaves started to change and fall from the trees. He was on his child's broomstick with his dad, and they were racing. Well, maybe his dad was going easy on him, but still, they flew over so many different places around and near their manor. Sometimes, they would land so they could run and stretch their legs. Usually, during those sprints, his dad would bring the invisibility cloak as an added measure of fun.
"Dad, why do some trees not have leaves during winter? Why do they fall off in autumn?"
"It happens every year; it's a seasonal change, sometimes to protect the trees. Sometimes, it happens too early if it's too windy. It happens every year. It can show time passing. Anyway, we should start returning home; your mum expects us back in the next hour."
"Dad, we have one more available hour. Can we fly even further?"
James would describe his dad as an excellent father and his mum as excellent as well. Despite all his resources and privileges, James wanted a sibling or someone closer to his age. There were some neighbor kids, but none of them were the same age.
Another of the best days and years was when his Hogwarts letter arrived. Going to Diagon Alley to get his wand, choosing an animal companion, and sneaking his broom into Hogwarts.
Meeting Sirius Black on the train was the best-by-chance event in his life.
Meeting Regulus Black the following year was even better. He was a bit jealous of Sirius since Sirius has always had a sibling. Sirius was James' first real friend. James was the sun, and Regulus and Sirius were orbiting around him. James loved the attention and not being lonely.
While his Marauders friend group was going through difficult times after the prank, James may have accidentally crossed a line by dating his best friend's brother. Quidditch and more Quidditch was the excuse, after all, with them being chasers and seekers.
Regulus Black always stayed Regulus; however, sometimes, he became Reg. Reg was his boyfriend. That was another best day for James—the day that Reg decided he could deal with James as a boyfriend and a partner.
Astronomy tower meetups, secret passageways, the Come-and-Go Room, and the invisibility cloak were all memorable days, moments, and months. Per usual, all good things have to come to a close.
"This has to stop; we can't keep doing this…James, you have to listen to me."
"Reg, stop speaking, please, don't leave! I won't let them hurt you."
"I'm not worried about myself. I'm worried about you; they're Death Eaters. They'll go after you, Sirius, your parents. You could be in danger if they know about you and how you make me feel."
"Reg, they already know about myself and my family's politics. We'll be fine. Please, let's rethink this in the morning, please, please, oh darlin', don't be a hero or martyr, don't you ever grow up, please, it could still be so simple, like earlier this year. Reg, please, don't do this."
"I'm sorry, James. I'm not good."
"Reg, no, stop; if this is the end, I am telling you now that I had the best days with you and only you!"
1979
'Kreacher, remember the plan, no matter what I say or do, ensure that I drink every last drop of it. Take the horocux, destroy it, and leave me there.'
'Kreacher dislikes this plan, Master Regulus, but Kreacher will follow Master Regulus' words. Should Kreacher deliver that letter?'
'No, Kreacher, wait to deliver it.'
June 1996
Feed Buckbeak, check the mirror, find Kreacher, toss family heirlooms, transform into Padfoot, run around, chase Kreacher as Padfoot, sometimes be an adult human wizard, and repeat. Add in annoying Snive—Snape if he dared enter. Luckily, the greasy git hasn't, but he does have unfettered access. Henever trusted the slimy Slytherin.
Also, prepare for Harry's arrival. He's almost done with his fifth year at Hogwarts—another horrible year if the letters and Floo conversations are true. Once he returns, we could focus on getting cleared and going to Quidditch matches. Hopefully, he can concentrate on his exams, Merlin's beard, I sound like Lily; how I miss them both, and just finishing the academic year.
Monotonous days in the Headquarters of the Order of the Phoenix. It was, well, still is, his family's residence. It wasn't much of a family, but it was who raised him for his first 11 years. Well, he raised himself and Reggie.
Sirius Black was in another form of Azkaban. Now, there weren't any dementors, but there were memories—mainly negative but some positive ones. Memories of his brother playing Quidditch in the garden, making Regulus and Kreacher's mud dishes, and pulling pranks in the corridors; well, those were a few positive memories. This place also reminded him of his horrible parents and terrible relatives, except Andy and Uncle Alphard, and that was about it. It waspretty pathetic, ugh, and don't mention Bella or Cissy. It reminded Sirius of " what could have been " this or that. What if he hadn't run away that night? What if he had stayed?
What if? What if? What if???? WHAT IF? WHAT IF? WHAT IF? WHAT IF? WHAT IF?WHAT IF? WHAT IF? WHAT IF? WHAT IF? WHAT IF? WHAT IF? WHAT IF? WHAT IF? WHAT?
His brother, Regulus. Reggie when they were younger. His young, impressionable, soft-minded, idiot brother was a sore topic, even almost 15 years later. Reggie was dead; he died 15-16 or so years ago. He was very dead, and despite everything that Sirius tried to think about, Sirius missed Regulus. He missed him similarly to how he misses James. James or Prongs, his other brother. The brother he chose. Similar to Reggie, James is also dead and has been for soon-to-be 16 years. Thank Merlin he still has his Moony. Well, at the moment, there's a slight disagreement, but it'll be fine; things will be fine in the future.
He would always say to Reggie, "Things will be fine in the future," but their joint escape did not happen as planned. However, they were kids younger than 10 when they planned their escape. Of course, it wouldn't have gone to plan; they didn't know anything. Sirius wishes that he and Regulus would have never grown up. Life seemed simpler but substantially worse in the Black House. It was awful, but at least he had Regulus then.
In a sense of unforeseen nostalgia, Sirius climbs to the top floor of 12 Grimmauld Place. He reads and disregards the "Do Not Enter Without the Express Permission of Regulus Arcturus Black" sign above the threshold. The bedroom had always been slightly smaller than his. However, Regulus truly copied the Slytherin common room, which looks ghastly to a Gryffindor.
Regulus was just like their parents, Sirius shudders. Sirius looks at the yellowing newspaper cuttings of disappearances, the quills on the desk, and the dried ink in the ink pot. There's no dust; Kreacher has been cleaning this room. The only thing the elf can do is clean his dead brother's room. It would feel and seem like Regulus would enter his bedroom any moment now and demand that Sirius leave, but he doesn't because it's June 1996, and everything that Sirius had is gone.
Crack! Ugh, the sound of Kreacher apparating; what could he want now? Maybe we could play Kreacher tag sooner. Padfoot would love to run around.
"Master Regulus wouldn't want you in his room."
"My idiot brother has been dead for years; I doubt he wishes or wants for anything. What are you doing, Kreacher?"
"Kreacher lives to serve the Black Family and cleans this room daily. Kreacher also has a letter for master Sirius."
"Give me the letter, Kreacher, and go away."
It's on old parchment, definitely yellowing. Sirius checks for curses since he can't fully trust Kreacher. Like his parents, the little blight would love to see him in pain.
The envelope still needs to be addressed, yet Sirius still opens and reads it. He immediately recognizes the handwriting. Although, he hasn't seen it in years since his Hogwarts days.
He reads it, but he doesn't fully comprehend it. After all, a 17-year-old letter from his dead brother is reasonably unexpected.
Dear Sirius,
I didn't know if you knew, so I'm taking the chance to say that I had the best days with you. I wished sometimes that we had never grown up and that it could still be simple.
I miss you, and I love you, I'm sorry .
RAB
Later June 1996
"Alright, Sirius. Welcome to being dead. It's a wonderful time. Fewer worries, honestly. And, the best news is that I haven't seen Orion or Walburga ever," a teen with black hair, haughty looks, and a slightly smaller build compared to Sirius says.
"Regulus," a surprised voice responds.
"Sirius, you've grown up, and you're still so you," as Regulus waves his hand in a way to explain how Sirius is so Sirius and also a little serious at the moment, probably because he's startled and recently deceased.
"I never did grow up, but I'm glad you got some time with Harry. James and Lily are somewhere around here. It's unfortunate but great to see you."
"Maybe we can try again and start over?"