Regulus' eyes went wide when Remus started to speak, because that was insane. He did understand Sirius' reaction. In fact, he probably would have done the same, but Remus' reaction was so outside his experience. "God, you are- you're one of a kind, Remus. You-" He cupped Remus' cheek. "You shouldn't; I wouldn't." He leaned closer and pressed his forehead against Remus'. "You are such an amazing man. Your ability to forgive and your empathy never fail to impress him. Qualities I despise because they are a sign of weakness, but they made me fall in love with you, because they show your strength. I love you, Remus, and I'm so sorry." He'd said it more time tonight than most of his life, and he meant them, but they seemed so little compared to what he'd done.
He drew back to look at the other man, and shook his head when Remus went on. "Don't do that. It was me, Remus. I might have been blind, even stupid, but it was me. That's what I'm capable of; that's what Severus is capable of. We might have changed sides, we might have stopped, but that's what we can do. I can tell you that if he touches one hair on your head, Greyback will curse the day that he came back to life, because I can and will do a lot worse to him," he said, darkly.
"Whenever you want, Remus. I told you; you can ask anything. I'll give you all the details if that's what you want. I've never- Admitting guilt that could send me to Azkaban forever isn't something I usually do, but I'll tell you anything you want to know." He didn't know how else to prove to Remus that he would have done anything, no matter the consequences, to make it up to Remus. However when the request came, he gasped. "Remus," he said softly. "You don't have to do this." Even as he said it, he knew that Remus was right. Greyback would use this to taunt him.
Regulus brought their joined hands to his lips and kissed Remus' knuckles before letting go. "We arrived that it was dark. It was summer and the days ended late, but that was fine for us, because we wanted to get you while asleep. It must have been past midnight. The spellwork around the house wasn't complicated at all, and it didn't take into account brute force. It didn't take us long to get inside. Greyback went in first. Death Eaters or not, we knew about werewolves' stronger bodies. He went to your room, while I and the other went to your parents' bedrooms.
"They were barely awake, when we stepped in. We bound them and brought them into the living area. Greyback was already there, furious, ranting. I knew we couldn't leave yet, just in case you'd come back. Greyback didn't want to leave for other reasons." He remembered the glint in the werewolf's eyes. "When I tell you that I forget that you're a werewolf, it seems ridiculous, but I worked with him often and he is a werewolf, regardless of the time of day or the day of the month."