"He remembers something of me," Sirius agreed "the off-my-nut-been-living-with-Dementors part. Oh, everyone's been very tactful about it, but even I couldn't live a merry twelve years and escape." He avoided Lily's gaze as she looked up at him. On That Night Sirius didn't remember finding Harry, though he knew with certainty now that Hagrid had been holding him. A whole family destroyed, because of him. Then Remus had told him that Harry had survived; twenty-one years without his parents, even without his Godfather. He knew he should feel guilty that he'd gone after Peter, that he hadn't insisted upon taking Harry or at least staying with him. But he couldn't - his hands still twisted at the thought of Peter. Perhaps it was the wrong decision, but he knew he'd make it a thousand times over.
Sirius tried to avoid thinking about That Night. His childhood home bore enough memories without him enforcing a loop of destruction into his mind. Above all things the portrait of his mother un-hinged his thoughts the most; it not only re-hashed old sentiments of 'traitor', but now was fed new information by Kreacher, or whatever she could over-hear. The constant commentary beyond death drove him to distraction, and none of them seemed to be able to remove it. Still, memories of that Wednesday in October found him in his sleep. Sometimes he'd watch the whole scene unfold; watch himself thrashing his bike faster, arrive to find the house torn apart. Other times he would see it happen, he'd see Voldemort enter the house. There was one uniting theme, he could do nothing to stop it.
He knew it was the same sense of helplessness that beset James. They all knew there was nothing James could have done, not without his wand, and even then... He'd stood to protect them, defenceless himself. But it wasn't enough, nothing any of them had done was enough. Sirius least of all, who'd handed them to Peter. He'd relinquished his control willingly.
Sirius was glad James and Harry didn't remember it too.
"Why do you think we remember it?" Sirius asked, "why do Remus and James have different memories?" Of course his and Lily's weren't the same, and Sirius' lasted a little longer than Lily's.