This chapter's all smut. Enjoy ;)
Severus slowed his movements, eventually just licking the head again. His left hand was left stroking the base gently. After a little bit, he let go, stood up, and wordlessly but gently pushed Harry to his knees in front of him. Harry moaned needily when he pulled off and pushed Harry to the ground. Snape's cock was lying stiff against his stomach, so he used his thumb to push it parallel to the ground and right in front of Harry's mouth. Looking down at the boy he whispered, "Suck me please, Harry..."
Eying the prick in front of him, all angry red and with thick veins, he knew that it was be the best thing he ever felt. Wordlessly, he licked the head gently, lapping at the precum that was beading at the tip. He moaned at the taste, his cock throbbing with need. He was all salty and musky, perfectly manly. He started lapping at the tip, swirling his tongue around the head.
Severus bit back a moan and started involuntarily fucking Harry's mouth, making sure to start out slowly to give him time to adjust his breathing. His hands grabbed at the mop of hair in front of him and he slowly ran his fingers through. The warm mouth willingly taking his member seemed to know exactly what it was doing to him. Harry used his tongue perfectly, making him squirm. He let the man use his mouth as he saw fit, keeping it open and easy to fuck. It felt amazing, and had his own cock leaking copious amounts of precum. Maybe he would be nice and rough with his arse, too. He didn't seem to have any reserves about fucking his mouth roughly. He whimpered at the image of being bent over something and fucked right through. He started sucking harder, using his tongue more.
Severus hoped it would feel this great when he was buried in the smaller man's arse, pounding him into submission. Harry's moans nearly sent him over the edge right there. However, he wanted to be deep inside the other man when he came. He stopped thrusting his hips and let out a weak growl, looking at Harry with lustful eyes. He tugged himself out of Harry's mouth with a slight pop and backed up several steps. Reaching down to drop his fallen wand, he murmured a lubrication spell directed at the other man's arse, pulled Harry to his feet and then engaged in a rough kiss, his cock pressed against Harry's stomach, his hands traveling down Harry's back to his arse, cupping and massaging it. A startled mewl escaped Harry's lips when he was lubricated, kissed, and massaged. He wanted Harry to make the next move, not wanting to seem desperate.
Harry was far past caring if he seemed desperate. Probably because he was practically gagging for Severus' cock. His senses were on overload and he was ready to have Severus buried balls deep into him. He backed up until his back hit a desk and he smirked. As he pulled away from the kiss, he smiled at Severus before turning and bending over the desk, legs parted in invitation. He breathed heavily as he waited to see what the other man would do with such a blatant show of need. If it made him look wanton then so be it.
Severus was shocked at the sudden invitation, at him looking so eager. So be it. He smirked and sidled up to Harry' ass, giving his hard-on a few deft strokes before grabbing Harry's waist and humping the naked arse. The friction caused him to moan and leak precum all over Harry.
Harry hummed with pleasure and mewled each time Severus ground against his arse. It felt amazing there, so he could just imagine how incredible it would be when Severus finally was in him. Sev's breathing became raggedy and heavy, almost in sync with the submissive. His hands migrated to Harry's hole; slipping in one finger, then two then three, he began to fingerfuck him to loosen him up.
A soft whine left Harry's lips when he felt a finger enter him, followed by two more. He clenched around them, wishing that they were bigger, thicker. They were nothing but a tease and Harry was about ready to beg for relief.
After a little bit Severus stopped rubbing his cock against Harry and lined it up with his hole, pulling out his fingers. Always one for dramatics, Sev taunted Harry with an agonizingly long pause. Then, without warning, with an almost inhumane guttural sound, he slammed himself into the other man, quivering with the sensations of Harry's ass.
A shiver went down his spine when things stopped for a moment. Harry nearly screamed with pleasure, his cock jumping and leaking precum when he was slammed into. "Yesss." He hissed, the feeling of being stretched and filled so quickly nearly pushed him over the edge. He forced himself to calm down a little and relax for Severus, wanting to last longer for him. "Severus..." He moaned softly, looking back at him with lust-blown eyes.
Severus continued to pound into the tight arse in front of him. He threw his hair back and moaned from deep in his throat. Keeping up the rhythmic thrusting for a little bit, he felt himself close to coming, having been so long since he screwed anybody. He locked eyes with Harry, their eyes matching in lust and depth. The thrusts came faster and more forcefully, pushing deeper inside.
Harry winced at first, the thrusts a little too rough and hard. He normally loved it rough, but it had been a hell of a long time since he had anything in his ass and it took him a moment to adjust. When he did, he was scrambling for purchase on the desk, moaning and crying out as his body was fucked like a cheap cock-sleeve. He loved every second of it, of being used for Severus' pleasure. His ass was getting slapped by the force of his lover's hips and balls, making him feel like he was getting spanked at the same time. Just that thought made him wail like a slut, clenching tightly around the man abusing his prostate. His cock was caught between his own body and the desk, adding more friction to it. He babbled as he was fucked, begging for more, encouraging Severus to use him, saying anything he could think of to make the man continue.
Reaching forward, Severus grabbed the prominent hips in front of him and pounded with an almost animalistic fervor. He was completely unaware of anything else; if he was hurting Harry, he didn't care. If someone was watching, if there was a battle raging around them, he wouldn't have noticed.
When Severus grabbed his hips and pounded into him brutally, Harry came with a loud scream of his lover's name, painting the desk with his cum. The final thrusts and insane tightness of Harry's ass sent Severus over, spilling his hot seed deep inside the other man. When he finished, he leaned forward, cock still inside him, and wrapped his arms around Harry's pale chest, resting atop him on the desk.
When Severus seemed to collapse on top of him, Harry was still panting heavily. "Fuck," he whispered, too fucked out to manage anything coherent.