He would never forget the day the letter came. It would be forever ingrained in his memory.
He had been sitting at the kitchen table, Kreacher serving him breakfast - bacon and eggs, he remembers; he'd been very excited about it at the time, but now he couldn't even look at bacon without the acidic taste of vomit coating his tongue - the unopened post still sitting in the centre of the table.
His eyes were on the House Elf as his mother reached towards the envelope, the name written in his brothers neat script with black ink on the cream paper. It was thinner than the other envelopes on the table - couldn't contain much more than a single sheet of parchment - but it was more than anyone had been expecting from Sirius on his first day at school.
He was still focussed on his breakfast when his mother read through it for the first time - there would be many read-throughs, the short letter passed around the family until everyone except Regulus, who never got to know the exact contents, had read it several times. He could just see her out of the corner of his eye, as he shovelled forkfuls of eggs into his mouth.
Distantly, he noticed her paling, eyes widening, hand clasping at her throat as though she were struggling to breath. She only really drew his attention - on what must have been her second read-through - with a choked off shriek as she leant back dramatically in her chair and thrust the letter into his father's face.
"Orion, have you read this?" she gasped, her hand shaking. He could remember thinking that it was a stupid question - of course his father hadn't read it; she'd been the one to open in - but he'd known better than to say anything.
"What is it?" he asked, his attention still on the paper, either oblivious to or ignoring his wife's distress.
"It's Sirius, he's- he's… Read it!" she stuttered, her tone shrill, as she pushed down his newspaper, tearing it in the process, and forced the letter into his hands. He let out a sigh, slowly trailing his eyes down the paper. Regulus watched, forkful of bacon held halfway to his mouth, as his father's eyes scanned the paper for a second time - third - face reddening with each read-through; eyes narrowing, lips pursing.
It would be several weeks before Regulus found out the contents of that letter - from his cousin, who had thought he'd already known - but that moment would always stick in his mind as the point where everything changed.