The Tower of Passion

"I'm happy to run in Mare form if you don't wish for a real challenge" Penthi taunted as everyone moved back to the beginning of the run. No one in her party was surprised this was happening and most seemed quite interested in the outcome, and Fiona was uncertain if she should be offended or aroused that her party members would want this to happen. Several centaurs had arrived to watch - and some Climbers as well. Non-thunderers doing the run was unusual, apparently. As in never happened. Probably cause of the two-foot horse cocks involved.

But Fiona could handle that. At least for the next few hours, the largest creature anywhere nearby. And maybe she'd win - although she wasn't sure she wanted to. She didn't think Penthi would appreciate it if she threw the race though.

"Please. I can outrun either of your forms." Fiona taunted back. She couldn't. Well, maybe if it was twisty, but she had been looking at Penthi's equipment for over a day, and... Well, she liked big toys.

"Stallion it is then. Need me to explain how it works?"

"First to the end? Where is the end?"

"You'll figure it out." Hooves stomping on the ground. Fiona was bigger now, her powerful muscles in her thighs flexing as she dug her toes into the dirt, twisting in for traction. Could she outrun a centaur? She wasn't certain, but she thought she had a chance. [Accelerate] had ended so she didn't have that advantage. She should be able to turn faster, and the canyon seemed fairly twisty.

Maybe she could do it.

Ash was brought in to signal the start of their run, gun raised as she stood between the two. The fox girl's eyes met Fionas, then Penthi's. She lifted her gun into the air.

Fiona wasn't quite sure if there was gonna be a countdown or not, and was slightly surprised when Ash just fired. Penthi wasn't, setting off at full speed as Fiona's toes pushed through the earth, her quads working hard to propel her through the canyon.

She loved the feeling of her muscles working, even as Penthi pulled away from her towards the first turn. The four-legged woman was forced to slow down in the sharp turn, and Fiona took her opportunity to not turn, but kick her leg against the rock to change direction rapidly, the short distance not letting the centaur get far ahead of her and the zig-zagging canyon and Fiona's powerful long legs letting her twist and turn rapidly getting a slight advance over the warrior. She smiled as her muscles burned from exertion, onlookers cheering her on from above.

Maybe she could win. Maybe 

And just as she had that thought, she left another turn at least a few strides in front of Penthi and all hope sank.

A straight.

To her credit, she didn't slow down. It took at least five seconds before the galloping centaur overtook her, disappearing in a thundering cloud of dust ahead of her. 

Fiona didn't slow, wanting to do a good showing. She did some showboating and flexing as she ran for the onlookers, and a few minutes later she got to a dead end, a large circular area, people looking on from above. Her friends there, her pet friend, every thunderer she'd met and more and seemingly every adventurer who had been on this floor stood at the edge of the canyon.

Penthi stood in the middle,  and next to her a wooden rectangle padded with grass on top. Penthi smiled as she saw Fiona patting the rectangle, smiling. She stood sideways, her enormous cock visible under her belly, and it took Fiona a moment to realize what it was.

A breeding mount. Infront of a crowd.

Fiona's loincloth tightened.

"So. I will let you back out human... Thunderer mare forms are used to this size, you're not." Her eyes were lustful, staring at the berserker. Clearly, her conscience required her to give Fiona the chance to back out, which she appreciated. It was not needed... The audience was interesting, but they were far away. And most of them Fiona would never see - and she'd realized her friends would find this fun to watch.  And Fiona needed 'help'.

"You clearly don't know me." Fiona taunted. In fact, the centaur was right - she had never taken any toys close to this size, at least in her pussy. That was at her normal human size. She was much, much taller now - basically a giant. Taller than most of the Mares she had seen. So in relative size, this was probably fine. Probably.
"Just... Pull out if I start shrinking. Quickly." Penthi nodded. Fiona wasn't quite sure how long she had left on her [Enlarge], the system didn't seem to have a way to let her know. If this was a game it would be 'immersion' here it was frustrating and dangerous.

She undid her seaweed loincloth and pulled her thong down, stepping out of her, letting lil Fiona flop free as she approached the mountain block. Someone wolf-whistled from above, and she looked up to see Liddy waving. Her friend's seal of approval helped her confidence, and she tried to strut towards the mounting block. Getting closer she could see two steel platforms on the side of it - presumably to make it so the mare didn't need to have the full weight of the stallion on their back, somewhere for them to place their front hooves. Hooves.

Everyone was gonna watch her get fucked by a centaur. And she was happy about it. She'd initiated it. She was dripping wet from the idea. She knew she needed it for her ability - six strength was an enormous benefit, and she could score a solid ability - although she was uncertain if she'd get rid of either she had. Qae had used [Snapshot in Time] before the race started - she was safe, Penthi was considerate, and this was necessary for maximum performance in the tower.

But she couldn't quite honestly say she wouldn't have wanted to do it even if she didn't need to. It was exhilarating - as a dildo connoisseur she owned several horse cock dildos, but none of them to actual size.  To be able to grow to the size where she could be... She would have paid a lot of money for this. Not like, with a living centaur - but for the ability to fit a toy this size. This would be priceless.

She bent over, noticing the mounting block had handles to hold on to. The centaurs took this very seriously it seemed - and it made sense, with such a big physical difference as part of the sexual dimorphism in their species. Even if every individual could be both. 

"Come on, I don't know how long this will last" She was probably fine - it had only been an hour or so, and when she'd used it previously. She didn't want to risk it though.
She felt the wetness from her pussy dripping down her exposed balls,  her cock pressed against the mounting block, jutting out slightly between her spread legs, thighs glistening from her juices.
It absolutely, definitely, most certainly was not because she was an impatient slut. Her collar glowed slightly. Oh... It counted herself. Good to know. She heard the clippity-clop of Penthis's hooves as she moved towards her. Everything was suddenly quiet, she held her breath, and then a quick movement, the sound of hooves, a loud crash, and the warm body was over her, hooves smashing down on the side of the block, enormous cock, tip wet pressing against her ass, sandwiched between Fiona and Penth. The Centaur bent down, a hand grabbing Fiona's hair as she gasped and moaned, wriggling under the heavy, hot body.

"You make a fine Mare" She whispered, somehow managing to bend down to just above Fiona, her horse body stopping partway up Fiona's back.
"And you're a perfect Stallion." Fiona said softly, eyes glazing over with anticipation.
"You'll have to guide me in." Penthi panted, clearly as fascinated by this as Fiona was. The human nodded, as Penthi took a couple of careful steps back, Fiona lifting her body and reaching around her cock and balls as she felt Penthi slide down her crack, the weighty, wide head landing in her outstretched hand. She gently held the heavy crown against her dripping folds her hands covered in juices.

"I'm ready. Mount me"

Penthi just grunted, panting heavily as Fiona could feel her moving forward, her folds being stretched as her fingers made sure it was lined up. Impossibly stretched, the flared head was finally in. The girthy cock moved inch by inch as Penthi took tiny steps forward, every increment enticing soft breaths from the berserker. After a moment of careful pushing, someone got impatient.

Fiona turned her head, looking up at the gorgeous woman invading her pussy, clear concentration on her face holding herself back.

"Push it all the way. I need it. Please. Fuck me. Fuck me now" Fiona begged. The careful, considerate entry was torture - she needed it hard, fast.
"Fuck... I will. Yes, Mare, Yes." Penthi grabbed Fiona's hair, and the heavy body lurched forward, the entire remaining length smashing into her as she screamed in pleasure, and mild pain. She was so full.

"Oh my... Oh fuck. Oh fuck it's so good, it's so thick how the hell is this." 
"You feel unbelievable... I... I won't be able to control myself."
"Don't" Fiona panted, as Penthi wrapped one fist around her hair, the other lightly gripping the back of her neck.

The enormous cock pulled out and slammed into Fiona with a power she had never felt, the human screaming in pleasure as the two sets of heavy balls slapped together, every thrust causing the cock between the berserker's legs to jolt, pushing out dribbles of cum staining the sand below her, stretching her pussy imaginable so and filling her in a way she imagined impossible. Even at her current size, this was intense, extreme, and wonderful. She'd forgotten the crowd, watching transfixed in silence as Penthi bred Fiona, mounting her and thrusting into her time after time.

It was not prolonged, both women dripping in sweat.
"Breed me. Breed your mare, I need to be filled, please it's the only thing I'll ever want." Fiona panted, delirious. 
"Take it, take all of it - Oh fuck, It's coming, I can't hold it back anymore oh----" Penthi roared in ecstasy, her hindquarters pushing hard into Fiona's muscular ass, hair pulled back. The sensation of the pulsing, hot girlcock inside her, cum filling her tummy, overflowing sending her over the edge as she tightened around the length, causing the centaur to shudder, more of her emissions filling into Fiona.

"Oh, I'm gonna fuc-" Fiona came from her pussy, the pressure on her balls making her cock cum as well the double orgasm causing her to shake, eyes rolling back in her head as her roar joined Penthi's, puddles of cum being created by the ropes shooting out from her engorged member, splattering into the sand, staining the mounting block. 

Penthi released Fiona's hair and neck, collapsing slightly on top of the human woman, before slowly retreating and kneeling down next to her. Fiona had no intention of standing up before Qae snapshotted her back... But not yet. She wanted to relish in this feeling, cum sloshing out of her stretched and abused cunt, the slightly painful very pleasurable feeling of her body readjusting, the glow. She needed a new way to stay safe, cause sacrificing this feeling was upsetting. 

A moment later, the crowd roared. Fiona looked up to where her friends were, and saw three of them in various stages of undress, groping and kissing each other, as Qae looked down seemingly orchestrating the threesome. 

She loved her friends. As friends, of course.

"No" Fiona whispered, as she fell asleep, naked and cum filled in front of a crowd of people.