Disclaimer: All recognisable characters are the property of JK Rowling.
Wakeful
Forgetfulness is an art.
Horace forgets so thoroughly and with such ease, now, that he is sure he couldn't actually locate the truth within his mind, if he were ever to seek it out.
It's like an extra layer of skin, the forgetting; something warm and protective as the gently dimpling fat that seeks to swallow his frame. It's a talent uniquely his, he likes to think; the ability to deceive oneself so comfortably and with such little tiresome effort. He simply doesn't remember - although his intellect is still sharp as edges, mind you - it's as if the things he saw and heard and did just whispered past, not bothering to cling within his brain with any lasting fortitude.
Horace Slughorn is no fool, however, and he is acutely aware of just what it is that wakes him, in the dark little minutes of the night, with a painful start and a heaving chest and blood rushing like a flood. He knows it is the memories, tugging their filthy little fingers within his breezy brain, and he resents it, terribly. They're not supposed to follow him, these mutinous, jagged thoughts; they're meant to be long gone, left with the dead in their dusty graves. And so he wills his breath to quieten, coaxes his legs to cease their quivering beneath the bedclothes and recommits himself, with muttered irritation, to the work of pushing all those splintery little thoughts down and away and out, out of his mind and thoughts and dreaming sleep. He rolls over in the bed, huffing and puffing like a piglet (or was it the wolf?), and shuts his eyes tight against the moon, as she dances a wicked jig on the wind outside his window. Sleeps comes, as always, and in the morning he shan't remember waking at all.