His cock was sliding in with obvious delight for both, her sounds that of a woman being fucked to her pleasure, the hot panting of bodies ramming against each other in mindless enjoyment. As they fucked, I could keep seeing her labia moving along his hard cock, gripping and caressing tightly, a perfect darkly pink area of female delight around his cock head before he went stroking deep into her again. Obviously, they had been fucking for a while, as her pussy had a certain look of satisfaction, one of the sexiest ways any woman can look, outer lips dark and puffy, her inner pink lips sliding wetly along the hard shaft sliding into her. Some things are simply truth, and the truth was, she was loving having her pussy fucked by the full length of Mike's pumping cock, which clearly showed how he was feeling about what they were doing together, his eyes shut in bliss.
The other truth was there was no way for me to resist what was happening in front of me, from her sexy breasts to her hot pussy to his fucking cock. And no way for me to stop drinking in the lust which was turning me on also. She first noticed me after several moments, long enough for my cock to have grown thick and obvious down along my thigh, and my hand to have moved to the bulge without much thought. My hands weren't that dirty from the engine work, since water, cleaner, and rags/paper towels were just part of the standard bus load - it broke down enough in ways possible to fix easily, in the classic way of old and used VWs, and cleaning up afterwards was just part of the basic routine.
I couldn't stop doing what seemed only distantly something embarrassing, and how her eyes kept closing while she was being fucked made it easier for me to keep touching myself, since she was so obviously lost in her own world of animal joy. As my cock grew rigid, the jeans leg enclosing it pointing downwards was getting uncomfortable while I stroked, and it seemed a good idea to unzip my pants to let my cock stand straight - and of course, be stroked, pumped, and rammed through my tight fist, completely lost in watching two people fuck. I was now also closing my eyes in pleasure, and at some point, when opening them, I noticed both Mike and Lena, tightly pressed together and quivering, each watching my cock in my hand.
At that point, we all seemed to take a slight pause, and I took the chance to take off my clothes and shoes, while Mike kept slowly fucking Lena, his eyes again closed in natural concentration on what he was feeling all around his still hard, slippery wet cock. Of course, I almost came then, touching my cock again, watching two people comfortably lost in their fucking, but was able to barely control the pleasure and finally settle into that comfortable state of less frantic horniness, the pleasure leading to a spreading satisfaction in a balanced measure, not a rushing flood of unstoppable orgasming. After having focused so completely on the two people in front of me, I slowly started to notice the larger setting, while also blissfully stroking my now completely turned on shaft and cock head.
For example, the scent of the room was an intoxicating mixture, dominated by the smell of her wet and obviously well fucked pussy. I find scents irresistible, and this was obviously a large part of what had been turning me on with such honest forcefulness, completely bypassing awareness at a thinking level. The smell of a woman's hot pussy is one of the true joys of good sex, and it certainly smelled as if she was at the peak of her natural cycle, and had been enjoying herself completely (she was using the pill at that point, so her peak was likely somewhat flattened). Of course, Mike was certainly adding his own note to the air, one I recognized after so many of our shared times over the years.
At this point, while still on her back being slowly and deeply fucked, Lena beckoned casually with her hand, and then said I should come closer, in a husky voice, with a certain rhythm connected to what they were doing, so we could all play together. Her legs were still completely spread, and it was obvious that she and Mike were still really enjoying themselves, that neither of them had any intention of stopping what they were doing soon - he was really grinding into her, and she was humping her pelvis steadily up and down, rubbing herself as hard as possible, both of them slippery from their fucking, her outer pussy lips dark and curling against her lover's shaft. I was hearing the sound of their wetly matted pubic hair, the sound of their slower but still obvious breathing, joining an intimacy which I had never experienced as an observer, only as a participant with a woman.
But participating was something on all our minds at this point, and as I kept moving closer, Lena reached her hand out, the palm up, fingers lazily spread, and she found and then touched my rigid cock. The thrill of that pleasure stopped my motion, and I just closed my eyes, but I could hear Mike start to fuck Lena harder and quicker than a moment before, and her hand tightened steadily underneath my cock head. The sounds of their fucking each other, matched with the wandering attention of Lena's hand on my cock, sometimes tightening, sometimes slack, not really focused on my pleasure, which wasn't necessary - experiencing what was going on, watching two people together in such clear ecstasy, was completely absorbing, and at some point, we all came in some impossible to know sequence, sharing ourselves so deeply in mutual pleasure that details were impossible to note in any way except for echoes afterwards.
I have only experienced such comparable pleasure a few times in my life, in other circumstances with other people, but this was my first and only time to see two people truly sharing a delightful fuck.