This is a bit of junk that popped into my head while reading. A missing moment from Prisoner of Azkaban: the minutes before Sirius Black attacks Ron in the dorms.
Sirius Black stood just inside the 3rd year Gryffindor boy's dormitory, looking around. How little it had changed. There were still the maroon four-posters, the red curtains, the squashy armchairs beside each bed. He smiled when he remembered how much abuse those poor chairs had suffered at the hands of himself and his friends. Those were better times…
He shook his head to rid himself of reminiscent thoughts and looked around again, this time with more purpose. The cat had been nonspecific as to which bed he was looking for, only that the boy had bright red hair.
He gulped, and stalked silently to the nearest bed, pulling the curtain back a few inches. Inside was a small, stout boy with a round, peaceful face. Sirius blinked. The boy looked an awful lot like an ex-girlfriend of his… how odd. He moved on to the next one. A plain boy with brown hair and freckles tossed fitfully – no.
He moved to the next one, parted the curtain, and reeled. James – James! Sirius almost cried out, before his head caught up with him. James was dead. He barely had time to register that tears were rolling down his cheeks before he sank down to a nearby chair, suddenly weak-kneed, and sobbed. He sobbed almost as hard as he had that fateful night thirteen years ago. Harry – his godson. His godson. The flesh and blood of his best friend – he had never seen him so close before – not since his was a baby, at least. He had only seen him once recently on a dark road, and then he had watched him play Quidditch. He would have made James so proud. The thought made Sirius cry harder than ever.
Another thought struck Sirius. What if Harry knew that he was Sirius' godson? God in heaven – what if he thought… what everyone else thought? He must. Who was there to set him straight? Harry must hate him. He must think that… that he had betrayed Lily and James. That he had intentionally killed them. Sirius doubled over in silent tears, head in hands. The thought was almost too much to bear.
That was what had made Peter's betrayal so, so much worse. Not only had he taken everything away from James and Lily and Harry, but from Sirius and Remus as well. Sirius hadn't even been able to speak to Remus before they took him away… to explain. Thinking of Remus made Sirius feel more despondent than ever. The Marauders had been the only friends Moony had ever had. Without them, he must have been almost as miserable as Sirius himself.
And all this was the fault of that foul, sneaking, worthless, double-crossing, gutless, cowardly, scheming, sniveling, conniving, traitorous, mendacious, pusillanimous, feculent piece of filth he had once called a friend!
That thought made Sirius straighten, wiping tears from his eyes as his anger once again got the better of his sense and despair. As he finally registered his tears, Sirius gave a soft, wry chuckle. Here he was, Sirius Black, escaped convict, mass murderer, crazed lunatic, crying at Harry Potter's bedside. Oh, the irony.
Emotions in hand, Sirius once again grasped his knife. Time to do what he had come to do.
Tell me what you thought - unless you hated it. In that case, spare me.