I chose to put this in the 'Mind Control' category rather than the 'sci fi' one mainly because of the title: 'Compulsion' indicates some sort of control, yes?
*****
Amelia Lake was feeling put upon. She had taken an evening cleaning job at one of the office blocks to help pay her way through college. As the 'newbie' and as an educated girl, she was the butt of the jokes, but she'd expected that. She'd expected to be given the tasks no one else wanted. But this was just silly. She'd been sent to the basement for some cleaning supplies; again she expected that; but had been told not to come back up in the same lift she'd gone down in. It didn't work properly coming up from the basement she was told.
'I have to stand up for myself,' She thought, 'so I'm not using the other lift at the wrong end of the basement.' She pressed the call button. The lift arrived smoothly, the doors opened and she stepped in.
'I knew they were pulling my leg' Amelia thought smugly as she stepped in and pressed the fifth floor button to return to the cleaning crew. The doors swooshed shut. And then things began to go wrong for Amelia Lake.
***
To Amelia's surprise the lift appeared to stop at the lobby level. Supposing that someone had pressed he call button she waited for them to enter as the doors slid open. When no one did she peered out and was shocked to see not the entrance lobby but what looked like a bedroom. She was about to step out to investigate but had an idea. She placed her mop bucket between the doors to stop them closing behind her, trapping her wherever this was. Only then did she cautiously inched her way into the bedroom, half expecting to be challenged. It seemed to be a perfectly ordinary room, even if the air felt a bit odd and strangely stimulating.
She looked around, and to the left of the lift door was a bed containing a naked young man with a fully erect cock. He was asleep. Amelia tried to look away but for some reason couldn't. Her heart rate increased and she felt compelled by some outer force to move closer to the nude form.
'What's happening?' she tried to say as her hand reached out to caress the rigid member. 'I wouldn't do this even if I was asked.' She thought as her hand moved up and down the cock before grasping the shaft and gently exposing a knob end now glistening with pre-cum. To her horror she found her head moving down and her mouth engulfing the shiny head, tasting the saltiness of the liquid on it. Her head began to bob up and down, her tongue teasing the shaft against her will. She tried to resist but found the compulsion to carry on too much. Whatever force was controlling her actions was too strong, so she gave up resisting it. Amelia found herself taking the dick deeper and deeper into her mouth with each movement down until the knob end was butting against the back of her throat. The only time she had attempted a deep throat before had caused her to gag wretchedly. Whether the compulsive force wasn't letting her this time she didn't know. Somewhat perversely from her point of view she hoped it was her. Even more perversely she was starting to enjoy the feeling of deep throating this anonymous cock. Now it was beginning to twitch and then suddenly her mouth and throat were filled with cum. She gulped it down, again unsure if it was her or the compulsion, but appreciating the salty tanginess properly for the first time. After a final feeble twitch the dick was spent, the balls completely drained of spunk.
Amelia was amazed.
'I didn't know I could do that' She thought, licking the last of the jizz from the deflated prick. The compulsion left her as she sat back and ran her tongue around her lips. She scuttled back to the lift, knocking the bucket in ahead of her. The doors closed and the lift continued upwards. Amelia leant back against the wall thankfully, thinking the strange interlude was over. Until the lift stopped at the next floor.
***
The lift doors pulled back and Amelia fearfully peaked out. This time the room beyond was an office, but not one from this block. Suspecting she was expected to do something here but not knowing what, Amelia sighed and strode out into the office. There was a man working at his desk. He glanced up when he heard her and smiled gratefully when he saw her. Amelia felt the compulsion flow into her again and found herself moving around to the man's side of the desk, halting by his side. He turned his seat to face her, still smiling but more hungrily now. She slipped her overall off, the compulsion moving her hands, leaving her in her Jeans and T-shirt. The guy reached around and cupped her buttocks, kneading the cheeks through the tight denim.
Amelia found that she was becoming aroused by his caresses, also knowing that this time it wasn't from the outside power. Her hands moved by themselves again, unsnapping her Jeans. The man pushed his hands down the back of her now-open denims, under her panties and once more fondled her ass. Amelia tried to stifle a moan of pleasure but the force wasn't having that.
The man grinned at the noise and then eased her Jeans and knickers down to her knees, exposing her carefully trimmed bush to his gaze. Amelia blushed inwardly at the thought of an unknown man seeing her like this. The guy stood and went behind her, bending her over the desk.
'Not my bum!' Amelia thought as she felt him fingering her tightest hole. 'I've never been buggered before. I wonder if I'll like it?'
With that thought Amelia realised that she wasn't fighting the compulsive force anymore; instead she was letting it guide her. Behind her, the guy was now working two fingers in and out of her virgin ass hole, gently stretching it out and coincidentally stimulating her more than a little. She groaned again. The fingers disappeared momentarily and were then reinserted covered with a cold, slick gel of some sort; obviously to ease his penetration, but the feeling was starting to excite Amelia. The guy worked his fingers around her butt for a while and then they were gone.
Amelia looked over her shoulder in anticipation and saw the man rubbing some more of the gel on his cock. She tensed for a moment, remembering being told that anal sex could be painful at first.