Harry's tried to wrap his mind around the whole "Severus is going to stick his cock up my arse" thing, but it's difficult to imagine. It's not as though Severus is particularly huge, regardless of the rumours that have circulated through Hogwarts since Harry was just learning how to touch himself in the so-called privacy of a toilet stall.
The man is more than adequately proportioned and while his girth is not abnormal, Harry still can't imagine the logistics of fitting Severus' cock into his much smaller arse.
At least not in any kind of comfortable sense.
He's tried to get himself ready. He wants their first time to be magical and rapturous like the books he's read seem to make it out to be. He wants Severus to want him back as much as he wants the older man. He wants to show his lover that he can do this for him, that he's not afraid of it.
He researches lubes. He practices putting his own fingers inside himself, but he doesn't really get anything from it other than a feeling of uncomfortable fullness.
At the suggestion from one of the twins, he hesitantly agrees to buy a dildo—a small, thin, barely more than a tube of hard plastic that he practices putting inside of himself whenever he is in the shower.
This latest experiment proves to be the most successful, actually creating small licks of warm sensation throughout his penis whenever he presses it into one particular part of his inner walls. He suspects that he's found his prostate, and for a wild moment he imagines himself verbally guiding Severus in to find it.
The idea is ridiculous.
At the success of his last dildo, he decides to upgrade to a more realistic sized one, but the sight of it terrifies him, and soon he is reduced to whimpering little cries as he curls up on the floor of the shower stall, holding his legs to his chest as he tries to avoid looking at where he flung the anal monstrosity.
Then finally, the night that he has been both dreading and anticipating is upon them. Severus has kissed him into breathlessness and they are both laid out naked upon the man's bed as strong fingers roam up and down his torso, before moving lower. He tries to relax, but his body is insistent upon trembling and all too soon, Severus has stopped and is looking at him with concern.
"Are you quite all right, my Harry?" Severus' voice is low and it rumbles against his chest in a way that makes him want to both melt and hang on for dear life.
"Yes," he whispers, trying to propel thoughts of trust and love up at Severus.
Severus' lips descend gently upon his own with a softness that most cannot see, and even more will never experience (which Harry is fine with).
"You need only ask, and we will stop," Severus whispers into his ear, making it tickle.
"But I don't want to," he argues, wrapping his arms around Severus' still lean torso. The man had gained some weight since the end of the war; not much, but enough that Harry no longer felt that he would be speared on the edges of Severus' bones.
He endures the feel of his lover's slick fingers moving within him, stretching him for something bigger. He tries, he really does, to stay relaxed, to breathe in and out as Severus instructs. The man loves him despite their history, and he loves him too, despite it, or maybe because of it.
It is for that reason that he tries to make it through the first few painful thrusts, through the point where he can relax, to the point where it becomes pleasurable for the both of them.
Only it doesn't.
And finally he has to concede defeat, and they finish the evening out with mutual hand jobs. Harry finally falls asleep, sated if not satisfied with himself.
He's heard from enough people, well Sirius and Draco Malfoy, that bottoming can be very enjoyable for both men. So why isn't it for him? Or is he just a freak once more?
. . .
He goes back to the drawing board.
It's interesting really; just how many gay porn shops can be found within Knockturn Alley. He buys several books and a few magazines and then he takes them back to his flat to read. What he finds is actually fairly surprising. Most of the men—the wizards—within the magazines seem to be far more obsessed with oral sex than anal. Hand jobs, like what he and Severus had engaged in the previous night, are common as well; mutual masturbation seeming to be just as popular as singular—although the latter is almost always accompanied by someone else watching.
The thought of Severus watching him so intently as he jacks off is enough to make him instantly and painfully hard. He has to go relieve himself in the bathroom before he can finish his research.
That evening, he goes back to Severus with a plethora of thoughts and ideas for where they can go next in their relationship.
"Yes my Harry?" Severus asks, pulling him closer.
"I've been doing a bit of reading . . ." he says, waiting for Severus to tease him, but the man only nods in understanding.
"I don't think anal sex is for me, but I have some ideas for some stuff we could do instead," he says, feeling inexplicably shy as he smiles up at Severus. The idea of his lover's eyes watching him has not left his mind all afternoon, and even now he can feel himself hardening against the dark cloth of Severus' robe.
"And what sorts of ideas would those be?" Severus' voice is inviting and one of his long fingered hands is slowly working its way down the row of buttons on Harry's robe.
"Have you ever heard of docking*?"
*Docking: The act of placing the head of ones penis inside the foreskin of another's penis.