A FFM threesome.

There were two women on their knees, a brunette and a redhead, looking up at the camera, a thick cock sandwiched between them. The women sucked and kissed around it, occasionally slipping off the shaft and tasting each other's tongues before always returning to worship their shared manmeat.

Your aunt had to look away for a moment and you glanced at her to see her grimacing.

"Jesus..." she breathed. She still didn't like the sight of a man's penis, even in video form. This especially seemed to be grossing her out, but that didn't really matter. You liked making her uncomfortable like this. It was doing wonders for the sensations on your cock. "That's... hooo..." she flashed her eyes up to the screen every so often despite herself. "Those are some... enthusiastic girls..." she said, her voice breathy.

"Sorry, Aunt Les," you said. "I just felt like something a little more..."

"Penisy?" finished your aunt. That made you chuckle. "No that's okay," she added, sounding sympathetic and leaning back into her seat. "You watch what ever you need to. It's okay."

You didn't say anything and just kept stroking, your aunt crossing her arms but now trying to watch with you.

"Camera work is pretty good," she said finally, opting to make her viewing of this threesome porn with her nephew somewhat academic. "Not easy holding the camera with one hand while...oh there she goes..." The girls in the video had moved on from the double blowjob to taking turns having their pussies fucked. They were both kneeling next to each other at the end of the bed while the cameraman fucked one girl and shoved his fingers into the other. The women wiggled their asses appreciatively, voicing their pleasure with moans. You barely paid attention to the screen, instead watching your aunt's face. Her squint relaxed as the scene went on, her expression shifting from total disgust to thin lipped discomfort. It was like she was trying to **** herself to acclimatise to the image of cock. "Those girls are hot," she admitted, letting her arms down and resting them in her lap now. "That redhead really can take a pounding huh?" Your aunt seemed mesmerised now, her eyes trained on the motion of the lucky camera guy's dick jamming in and out of the redhead, who was furiously rubbing her clit between her legs.

The girl then cried out, apparently reaching climax, slumping against the bed while her fingers became a blur. The guy pulled out with a groan, his cock shiny and throbbing. You felt your aunt bob next to you. "Jesus that thing is so... veiny... yehck..." she muttered. Then she looked surprised at herself and her eyes shifted to you, noticing you watching her. "Oh sorry! I am I distracting you? I'll stop... sorry!" said your aunt, seeming embarrassed. You shook your head, the pace of your stroke making the blanket over you an undulating wave.

"No... not distracting at all..." you said, managing to not groan your words. "I'm... I think I'm getting close." You aunt nodded and started to shift. You clutched at the blanket and said, starting to grow breathless, "I'm gonna stand up."

"Okay okay!" your aunt said, holding her hand up before you could move. "Just wait for me first." She quickly got down in front of you on her knees, brushing her bangs from her lovely face before closing her eyes. "Okay I'm ready," she said then opened her mouth.

You pulled the blanket away and stood, stroking your cock with your head aimed at her tongue. You saw your aunt's eyes attempt to peek at you, to look at your cock, but she only managed a parting glance before she slammed them shut again, head shaking slightly. Whatever. You unloaded with a grunt, hot gooey cum splattering onto your aunt's tongue. She didn't flinch this time though and you saw her instinctively reposition her neck to ensure she caught the whole load fully. You stroked your ropes out into her trained mouth, watching her tongue be coated in white, the wobbly jizz that built up spilling over back of her tongue and down her throat thanks to gravity. You pinched the last drop out of the tip of your cock into her mouth with a shiver then pulled your pants back up, slumping into the coach with a sigh.

You watched your aunt close her mouth, her expression one of pure indulgence as she swallowed your creamy load. Her eyelids fluttered open and she looked at you, her cheeks rosy, and in that moment she was the most beautiful creature you had ever seen. You saw that her fists were clenched, wringing the bottom of her tank top and pulling it down slightly so that you were treated to a full view of her cleavage. You felt like you could give her another load right then.

"You better go... uh.. get yourself off," you said, remembering the treatment plan. She nodded and stood.

"Right okay." She glanced over her shoulder at the porn action still going on the TV, the camera guy now railing each girl on the bed, one was laying on top of the other, a stack of pussies for him to fuck.

"I'll wait in the kitchen," you said, getting her attention again. "When you're done I'll take your sample there."

"Right," your aunt replied again, nodding. She left quickly and disappeared into her room.

You gave yourself a minute to come down from the high then closed the laptop and went to your stack of travel cases. You found a small one and took it over to the kitchen counter, unclasping it.

Inside were a few sets of research and testing devices. One was similar to the first device you brought the other day to test your aunt and you took it out, placing it onto the table as well as a box of mouth swabs. This one was slightly better for taking readings from a patient sample... but there was also some other devices in the case that could do a much more accurate and thorough job. They were a little more intimate in nature however. You wondered if you should suggest using these to your aunt. It would get the best data...