Threesome in the changing room

After an hour of volleyball the other girls began to make their way off to lessons, before just Grace, Kate and I were left. I followed Grace to the changing rooms, Kate hanging back to speak to the swim teacher.
"Aw look, Sally's left you a towel, we'll shower then you can dry off and head to lessons." I glanced at the towel lying next to a pair of pink underwear on the bench, before realising two things, one: the pink panties on the bench were next to a school uniform and bra, meaning that Sally was still here, and two: Grace had said 'we'.
"Er, I'll just wait her for you to get showered, do you-" I started, but Grace interrupted.
"Don't be silly, we don't have enough time for you to be waiting for me to shower. Just don't stare too much." she winked at me, and as I started to ask about Sally she took my hand and led me to the shower area.
Going on ahead I picked a shower in the corner and was pleasantly surprised when Grace followed and took the shower next to me. We both turned our showers on and took a moment to adjust the heat settings, but as I turned to glance at her I saw that she had both her hands behind her back and was toying with the knot on her bikini top. "Hey Zach," she said sweetly, "would you mind undoing this knot for me I just can't seem to work it out." I stepped nervously towards her, my cock twitching within my tight swimming shorts, and reached my hands out for the only thing keeping those gravity defying tits constrained; the knot was easy enough to undo, but as my hands pressed into her bare back Grace let out a contented little moan, "Oo that feels good Zach, my muscles feel really tight, how about a massage?" Shocked, my hands seemed to start moving of their own accord across her back, massaging as much skin as I could get my hands on, receiving lots of little moans for my efforts. Once I'd reached the small of her back, a few inches above the line of her bikini bottoms, I moved to work back up her back, but felt Grace's hand reach back and grip mine, keeping it in place, "keep going" she said. I wondered about the logistics of this as Grace moved my hands round to either sides of the tiny piece of fabric, to the two knots on either side.

"Untie." was all she said, her voice taking on a commanding tone. I pulled at both knots simultaneously, hands shaking somewhat, and it seemed as though these had been tied considerably looser than my tying of her top, and they suddenly unraveled, the bikini bottoms falling to the floor. Grace was left standing naked in front of me, facing away from me. My eyes were immediately drawn downwards to her incredible butt. It defied gravity as much as her tits, especially outside of the constraints of the swimsuit, and I wanted nothing more than to sink my hands into its bubblyness, grasping on as I pulled myself inside her... I'd let myself get distracted and was brought back to my senses by Grace nudging my hands downwards, but as she did so I realised that my mind wandering had had more than a little effect under my swimming shorts - the tent was threatening to poke Grace in the butt, and I reshuffled backwards as my hands began a shaky descent. But her hands moved from mine further back, behind me, as she pulled me back into her, my cock under my shorts making a considerable impression on her butt. but she didn't seem to mind at all - rather, she continued pulling me forward until our bodies were smooshed together, my hard cock resting between the perfect globes of her butt.

My hands remained between us and firmly planted now on her butt, massaging away, and continuing to elicit increasingly loud moans, until suddenly she swiveled around to face me. Her face was flushed and the water had run cold. Her body was covered in shampoo lather that something, oh something, had distracted her from rubbing in. "How, Zach," she began, "do you intend to shower with quite so many clothes on?" Knowing that the answer to her innocently posed question was an action rather than a reply, my hands moved to the knot at the front of my swimming shorts, but Grace beat me there, quickly untying it, before letting her hand wander slowly downwards. As she tenderly descended her hand she moved slowly towards me, her hand getting crushed between the two of us as she closed the distance between our lips. Just as her hand reached the shaft of my rapidly growing member through my shorts, she reached close enough to me for our lips to touch, and as her naked stomach pressed her hand more firmly against me, her lips met mine and the dual sensation of her hand and lips overtook me, and groan escaping my lips into her mouth, into which my tongue had slipped. She pulled back, her hand descending back down my cock, lips pulling away from mine I groaned this time at the loss, but they were quickly replaced, again with a long, slow, stroke of my dick. She repeated this for a minute, until the two of us grew impatient. We both had the thought at the same time; I pushed her away from me and she dropped down onto her knees, pulling down my swimming shorts on her way down. My cock sprung up and almost the second after it had left the confines of my shorts, it was in her mouth, a gasp escaping my lips as a second later Grace began to suck; taking it in and out of her mouth at a speed that made me weak at the knees she was the definition of hungry for dick, and as she continued and my hips made involuntary forward motions she continued to take my dick further into her mouth, until finally she pulled me out of her, **** and breathing heavily, and looking so incredibly hot. Slowly recovering, I wrenched her to her feet, and caused her to let out a little squeak as I didn't stop when she was standing, rather kept lifting her until her butt was resting on the shampoo ledge, placing her pussy at an almost perfect height for my mouth to get to work. Her hands gripped my hair the second my tongue touched the lips of her pussy with an almost indiscernibly soft kiss, but as she tried to pull me into her I pulled away, kissing my way away from her pussy up her thigh. She let out a groan of simultaneous pleasure and frustration as my lips approached her pussy again, only to be waylaid to her other thigh, kissing close enough that she still moaned, but not enough that she was satisfied. Just yet.

"Zach, please. Please. Fucking eat me ou-" her words were cut short with a shriek as my tongue suddenly attacked her clit, my middle finger at the same time pushing though her lips and inside her, quickly gaining pace as I swirled my tongue around her clit. She began a steady stream of moans as my ministrations continued.