Short story

"Bend your back, down, relax it."

She bent her bare back, not like an 'n' but like a 'u'. She looked at him. Her delicate underwear was all she wore, highlighting slender little curves. She looked so delicate and feminine and petite. Oil shone on her lovely curved back.

"Stay there," he said.

He stepped up on a part of the gym bench. And swung astride her back. Naked.
She braced to hold him. Her little muscles trembled at the start. She wasn't nearly his size.
Blood rushed away from his head. It concentrated elsewhere. This is what he'd wanted! For so long. And now, he had her. Both willing and forced.
"I'm going to ride you, pony girl," he said softly as he sat there, high astride her. "I will ride you until you can't take any more. I will ride you until your arms shake. I will ride you until your little body collapses under me. Maybe even that won't be the end. I'll put you back on your hands and knees and make you bear my full weight some more."
He was rewarded with a little shiver.

"Lift your arms up and put your hands on the bar there."
She shuffled forward on the gym bench. His legs hung down on either side of her. His body seemed to be concentrated in the parts of him that pressed against her skin... thighs against sides, backside and groin full weight pressed into her slender bare back. He felt like parts of him were leaping; adrenaline flooded through him.
She put her hands on the bar, which was maybe a foot higher than the rest of the gym bench. It made the curve of her back dip even more and he pressed fully against her back now.

"Arch up."
She strained, and arched her back up with his full weight astride it,
"Arch down."
She arched it down again.
And he rode her for a little while like that. Softly arching him up and down. He could feel the effort it took her slender little arms and body to do it.

"Giddy up!"
His crop smacked her backside. She moaned, soft and high. She wasn't sure what he wanted. She began to pulse her body in a gentle rhythm under him.
She could feel him, so heavy astride her back. His thick, strong thighs pressed around her naked sides. His throbbing arousal against her skin. One of his hands in her thick hair, pulling back as if to make the arch in her back even deeper.
She felt her little muscles strain to hold him, to obey him. She felt almost crushed by his size, his weight. It was hard for her to move. His crop had left spreading warmth across her bottom. And yet... And yet it wasn't all bad. The fact that it was she who had caused this big man to feel so crazy with want and desire, that she pleased him, that felt good. The skin on skin felt good also, especially as his was so... heated. It was erotic in its own way. And she felt utterly dominated, overwhelmed. Feelings she could consider later. But oh, she couldn't take it for long!

He rode the slender little body, feeling her strain and quiver to keep obeying, feeling her back so wonderfully curved under him. He whipped her on, and felt her delicate body move in a rocking rhythm, back and forth, back and forth, weak and delicate yet enough to rock and grind him on her back so very, very lewdly.
Ohh, yeah... He moaned out loud and couldn't help urging her on again. He was rewarded with a soft little gasp from the soft voiced girl underneath him. She had no choice. She would carry him until he exploded all over her back. He would force her on, make her get up if she collapsed... The heat-driven thought-feelings cascaded through his brain.
Back and forth, with a little bit of up and down, went her rhythm. He was slid and thrust against her back in time with the movements. He pressed himself into her back, leaned into her, hands in her hair, and growled encouragement into his petite pony girl's ear. It was going to be far shorter than he'd hoped. But he didn't care.

She stopped moving, panting, arms aching, her delicate body trembling with the effort of just holding her up. She couldn't keep the movement up. He sat there astride her, perfectly still, with his cock pressed deep into her upper back in that rather lovely position, and felt her tremble. Savouring the moment. Heat was rushing through him. It wouldn't be long.
"That's okay..." he whispered. "stay like that.. but don't collapse..." And he began to move on her, in his own rhythm, riding her bent and oiled back.

She cried out and used every little bit of her delicate strength to try and hold him up as he rode, grinding into her. Her arms shook. Still he rode her, forcing her to either move with his movements or fall, almost bouncing on her back as the electricity rose through his body.
He drove his hips against her little back as climax overtook him. Groaning.

And as he sat there, trying to recover from the violent moment, her strength gave out completely. Her limbs buckled and she collapsed on the gym bench.

He laughed. "Poor pony," he said, and kissed her on her sweaty head. "I rode you too hard."

THE END