As always. Huge thanks to my beta, MrsBates93
The first time was in first year on the fifth day of term. He had already received a howler from his 'loving' parents about how he was a disgrace to the Black name for being sorted into Gryffindor. The entire Great Hall had heard it and was now muttering amongst themselves about it. His cousins, Bellatrix and Narcissa were sneering and making loud comments.
But the howler wasn't the only mail he had received that day. In his hand was a letter from his younger brother Regulus, he had recognised the handwriting immediately. Sirius couldn't stomach another abusive letter, so he had put it in his bag, where it would be moved to the inside cover of a Potions book, which would then find its way underneath Sirius's bed where it would spend the next seven years.
Sirius would regret never opening that letter.
The second time was in third year. Regulus had just been sorted into Slytherin and upon looking at his brother for a sign that it wouldn't change anything, he found Sirius avoiding his gaze, determinedly looking down at his empty plate.
Sirius would regret not giving Regulus the sign that he needed.
The third time was in fourth year after a Quidditch match. Sirius had hung back to ask Regulus if he was staying at Hogwarts for Christmas. He had been met with a sneer and a harsh comment about being a blood traitor before Regulus had stormed off towards the castle.
Sirius would regret not seeing the truth in his brother's eyes.
The fourth time was in fifth year. It was the morning after what would later be called the 'Whomping Willow' incident and both James and Remus were refusing to talk to him, even with Peter relaying messages back and forth.
Sirius would always regret the hurt and betrayal that he had made Remus feel.
The fifth time was about two months before Lily was due to give birth to Harry. The threat of Voldemort was rising and the Potters had just found out that they needed to go into hiding. James had asked Sirius to be their Secret Keeper but Sirius had convinced, even begged James to ask Peter instead.
Sirius would regret ever trusting Peter Pettigrew.
