Over the lips, past the gums

To Harvey, it almost looked like slow motion as the stream of alien jizz arced towards its target; Diane's face was still shocked as she realized what was heading her way. She foolishly opened her mouth to scream in panic, giving the slime an easy shot. Her hands here too slow to defend herself as the thick glob seemed to maneuver itself to avoid her reaction. The symbiote filled her mouth obnoxiously, puffing her cheeks out as her tongue battled the foreign object. She expected to easily spit it out, preferably on her disgusting roommate, but the liquid wasn't moving as she expected it to. This wasn't her first time having a mouthful of cum, but this one seemed to have a mind of its own. She kept her throat as tight as she could, but the slimy substance seemed to fit through even the smallest breach in her esophagus, until the young woman had to relent just to avoid suffocating. She coughed roughly as she felt the thick lump travel through her, and her mouth felt coated in the stuff. "What-*cough* the fuck?" She hoarsely choked. "What is wrong with you?" She smacked her lips and tried to spit away the taste. She shivered in discomfort, acutely aware of the deposit Harvey just made at it sloshed around her stomach.

"Are you ok, Di?" Harvey was still sitting on the floor with his pants at his feet. "I'm so sorry, but I can explain." Technically true, but he knew she would never believe him. "Last night, I got really drunk, and-"

"And it made you a sex-crazed psycho??" She scoffed, still spitting into his floor. "I have to brush my fucking teeth, and you have to find a new place to live!" She shivered at the uncomfortable feeling all over her body. She felt dirty and used, inside and out, and wanted to throw up. To her confusion, as she reached the doorway, she stopped dead in her tracks. Her feet wouldn't cross the threshold, barely shuffling in place like she was an antsy dog waiting to relieve itself. "What the fuck?" She mumbled to herself. She turned back to her roommate with an accusatory glare.

"Perfect, Harvey. Now we must produce more of me." He heard the alien voice again echoing in his head. Apparently not all of it jumped into Diane. Like earlier his cock quickly engorged, straining the muscle as it prepared for round 3. Diane's eyes locked into it immediately, renewing her disgust, but instead of trying to flee she slowly sauntered closer. Her look of hatred turned to confusion then panic when her hands gripped the hem of her sweater and lifted. "Just let me do all the work." A new voice but the same speaker. The alien creature was now copying Diane's voice instead of his! "I didn't realize the sexual dimorphism of your species, but I'm guessing you'll enjoy this voice better." It was right; this was a much less intimidating voice, but it was still surreal hearing it without a visible source. As he pondered this great mystery, his roommate found herself unable to take her eyes off the thick, twitching meat of Harvey. Why did her body seem so drawn to it, and why was she seemingly getting ready to mount it? Who was that woman she suddenly heard?

"Harvey, something's wrong. I'm not doing this." This currently being a slow strip of her denim, leaving her in a pair of cute, striped underwear. "I can't control myself." Her shock was oddly arousing to Harv: someone being so turned on that they can't resist their lust was something any man would appreciate, but he knew it wasn't just a case of weak will.

"Stop this." He begged the symbiote out loud. "It's not fair to her." He hoped he could reason with the thing seemingly bent of conquering his planet. Diane looked at him like he was crazy.

"Don't you think I'm trying? Who's 'her'?" Now she was unclipping her bra to let her teardrop tits hang free, their nipples hardening from the cool exposure.

"I assure you, all parties with find this most agreeable. I merely need to resupply my form with matter. Your genitals produce the perfect mixture of nutrients for me, and intercourse is the quickest was to generate it. You both need only to relax."

"Who's saying that, Harvey? Is this some sort of prank?" She looked around for the hidden person while her body moved on autopilot, squatting over the still prone man and lining up her mound with his shaft. She didn't realize how close they were until her noticed her hands shifting her panties to the side to reveal her moist slit. Harvey recognized the wetness as his new parasite. It had spread throughout her entire body to gain control while leaving her cognitively intact. "Nonononono." She groaned as she descended. Rationally she didn't want to fuck the guy who had so crassly and literally cum at her, but her body was reacting like it was the only thing she wanted. "Fuuuuuuck~" Her resistance melted as her pussy slurped up his cock like the missing piece of a puzzle. Harvey felt the dripping slime of the alien jump from her lips to completely lube up the cock and almost pull it into her. He also moaned at the incredible pleasure the symbiote provided. His eyes crossed and his vision almost faded, but with inspired vigor, he began to thrust his hips.

"You see? I am a generous lover. No harm will come to either of you, so just enjoy it."

"Harvey..." His sex partner panted his confused heat. "What the Hell is ~Ah~ going on?" Diane tried to remain composed as a sliver of drool hung from her lips while she rode Harvey.