Just a bit of a something I wrote because I was feeling festive (after Christmas, yes). I hope it gets the point across, though I don't know if it does.
When the nights are dreary and the breeze carries loneliness through the old mausoleum, Sirius can wrap his arms around Harry and almost believe, if only for a few moments, that he's holding James again.
He should be sorry for this, he should feel even the slightest bit guilty that he's using Harry because he looks so much like his father. He should feel guilty because he knows that James never would have approved. He remembers, then, that it doesn't matter what James would have approved of, because if James was still here to disapprove of it it needn't be happening at all.
He wishes, sometimes, that he was sorry, that he felt guilty. It would mean, perhaps, that he wasn't as mad as he seemed to be. It wasn't right, and he knew this, but still it happened. And every time, Harry closed his eyes and didn't speak. If he did, it would break the illusion, and he hated to see Sirius in pain.
It is much easier this way, to be there for his Godfather in a way his father once had, to lose himself so easily in the way Sirius looks at him and touches him. And it seems, for a moment, that he can almost believe that these looks and touches and kisses and words were meant for him, not his father.