All the while during Remus's rant, Sirius was preparing a million and one retorts, many of which would leave him far too vulnerable for his liking. Many of which would have been Sirius yelling about how fucking unfair Remus was being, that yes, he made a mistake that he would regret for the rest of his fucking life, but how dare Remus assume Sirius ever thought him to be anything less than the most perfect fucking human being on the planet, and that he didn't bloody well love Remus more than he had ever thought himself capable of loving anyone.
It was all right there, in his frenzied, enraged, desperate mind, and his mouth was opening to say the words before Remus had even finished.
And then Remus finished.
And with that final, biting question, the gears stopped turning, the wheels skidded to a stop. Everything froze, everything inside Sirius seized all at once, and everything, everything hurt. Sirius didn't even have time to consider what was happening before his clenched fist was flying forward, smashing into the nose of the boy he'd sworn never to hurt.
Time started up again with a painful jolt, and Sirius staggered backward, that same guilty fist unfurling as Sirius covered his mouth in complete shock and horror.