Percy's bedsit had a single window facing the blank wall of the next building. Like many wizards in cheap flats, Percy used a view-spell to give himself something interesting to look at. The easiest setting was simply the view of the street which was blocked by the building next door. Sometimes, however, he gave the window the view of various parts of London, setting the spell to rotate randomly throughout the sights.
Exactly once, he'd given it the view from his old bedroom window at the Burrows.
More often than not he actually preferred the empty view of the wall just a few feet away. It was soothing, the blocked view offering the sensation of a bit more space while maintaining the sense of privacy.
That privacy was important because sometimes Percy liked to stand in front of the window, naked. Only at night, when the chance of anyone glancing up and seeing him was reduced to nearly zero. That 'nearly' was enough to make it seem daring; enough to give him the thrill of the illicit. Not that being caught standing naked in front of a window was all that daring compared to some. To his brothers, he thought, it would seem like nothing.
But to Percy it was everything. To strip himself of his robes and undergarments and stand fully nude in the open air where anyone would wandered into the narrow alleyway could, in fact, look up and see...
It was exciting. Arousing to the point that simply thinking about it during the day would get him hard. Actually standing there at the window made him hard enough that he barely had to touch himself to come.
He usually avoided touching himself for as long as he could. Standing naked in front of his window was arousing; standing naked in front of his window with his cock fully erect made something inside his brain burn.
He would stand there for as long as he could, letting the night air touch every inch of his skin and straining his ears for any sign at all that someone was in the alleyway below.
At first, he had kept his robe at hand, ready to pull it into place in an instant. Now, after living in this flat for almost a year and having spent countless nights just like this, he left his clothes scattered on the bed behind him. His wand was on the table across the room -- only a few steps away, as tiny as his flat was. But if anyone did see him it would take him a minute, at least, to cover himself.
The lack of protection made him even more aroused. Knowing that if caught, he could not immediately deny what he was doing... Percy's knees would shake and his head would get slightly dizzy. He would have to put out his hand, brace himself against the window frame.
Leaning so close to it that his cock would be sticking outside. Past the boundary of his flat, and Percy's breath would begin to hitch. And he would stand there, still not touching himself if he could at all manage it. If the arousal were not screaming at him so loudly that he'd be jerking off without even realising he'd given himself permission to touch.
If he could manage, however, he would stand utterly still and leave himself utterly open to be seen by anyone who cared to look.
And sometimes, afterwards, being ignored the next day would hardly matter at all.