Regulus has long ago accepted that you are the only good in his life. Or, at least, the only consistently good thing, ever since you met him. It had been at a dreaded, hated Quidditch practice, the first one of his fifth year. You were there. A new addition to the team. He had been apprehensive, of course (he wasn't one for change), but over time, Quidditch because not a thing to hate, but a thing to look forward to. Because he'd get to see you.
Everything else always falls away, disappears with time, Regulus learned over the next few years. His parents, who he used to love, eventually became people he can't bring himself to look at. Sirius left right when Regulus needed him most, abandoning him for a better life that Regulus wasn't invited to. His friends, yes, they were still there, but the majority of them now couldn't meet his eyes. Ever since he was forced to join the Death Eaters. Ever since he had to carry the Dark Mark on his forearm.
You didn't run, though. You didn't fall away. He didn't give you a chance, really, not when he was so desperate for someone to understand and to be by his side. He had pulled you aside after you were eerily silent towards him at a Quidditch practice. He had told you everything, even the things he swore never to tell— he begged you to understand, to see that this wasn't what he wanted, and if he could stop it, he would. And, by some miracle, you stayed. You listened, and you stayed by his side. And that just made him fall even more in love with you.
You had told him to stay safe as he left the little house you two share, just as you do every morning. He had promised you he would, kissed your knuckles, and said he'd see you later tonight. This was the time of the day he hated the most. When he has to leave the warmth of you to go to the hell he is forced to call "work." Endless meetings about blood purity and dictatorship and whatever the hell has angered the Dark Lord that day. The only good thing about it? He gets to anticipate the moment that he is back with you at home.
"Regulus," the Dark Lord had demanded near the end of the day. Regulus, who had been remembering a particularly fond day he had with you a few months ago, flinched just slightly and looked up at the Dark Lord, his insides turning cold. He never spoke to Regulus this directly before. "You're distracted."
Silence. A nervous panic settling just in between Regulus' ribs. He could feel the eyes of at least two dozen people on him, waiting for the Lord's next words, but he didn't look away from the man's snake eyes. His thin lips curled into a smile that couldn't be described as anything other than cruel, an expression that only worried Regulus more.
"This person who's distracting you from work," he began again. "I want them dead."
More silence. Horror. An inescapable fear that seems to wrap itself around Regulus' throat. And the Dark Lord merely grinned. As if telling a joke. But Regulus knew he isn't joking.
"You will do it yourself," the Dark Lord continued, "or someone else will. Your choice."
He begged for a long time. Wailed that you weren't a distraction, asked that the Dark Lord change his mind. But he didn't even look in Regulus' direction for the rest of the night. Which is maybe why, now, as he opens the door to the house, his cheeks are wet and his free hand is trembling violently, his other hand wrapped tightly around his wand. He glances around the room for you, sure his knees may give out before he makes it to you.
"In here, love," he hears you from the kitchen, and after a long, suffocating moment, he forces his legs forward toward the kitchen. He sees you setting the table for you and him, looking so dreadfully soft, so beautiful. You turn towards him, mouth open like you're going to say more, but when you see him, holding his wand up toward you, eyes wide and horrified, you stop. Your hand instinctively reaches for your own wand on the counter.
"Expelliarmus," Regulus forces out before you can raise it, the wooden thing flying in the opposite direction. And God, he has to do this.