Your body shifts left and right, rocked by the Galarian Rapidash's shifting rump...the straps binding you taunt and leaving you immobile as your body body is flush against the horse pokemon's enormous hole, facing directly towards the horse's ass.
The straps, which were obviously made to ensure that being flung about and against the butt once the equestrian pokémon began running so that Celestia wouldn't inadvertently kill you were taunt. It was not quite as severe as a wedgie. But you were lodged point blank against the hole, touching it, but not firmly mashed into it.
And worst of all was the helplessness of the waiting as you're left dangling from the horse' tail, uncomfortably close to her backside. Your body hangs quite close to the dock of the tail, but far enough from the base for you to be at about, well, just the worst spot one could imagine to be; all you could hear were the ominous THUDS sounding out with every step of her hooves.
For her part, the country girl riding Celestia doesn't even bother pretending to acknowledge you. To her, you were just a simple little decoration. A tiny little living trinket. Just some arts and crafts tool.
"Awright...C'mon Celestia, up fer another run, girl?" The giantess above you asks the pokemon.
"No! No, no, no, no, no, no! No!
No, no, no, no, no, no! Oh, no, no! No! No, Please, no! This can't be happening! I must be dreaming! Come on, wake up! Come on! No! No, I'm not ready!" you screamed. "Celestia, PLEASE DON'T DO THIS TO ME!"
"Oh?" The cowgirl muses, finally giving you her interest. "Well now...most Tinies beg ME when their abouta' be gettin' horseassed. But you, li'l varmint...you're beggin' Celestia? Interestin'...."
Hearing this, you thought your words reached to her humanity, but alas your hopes were dashed as you then felt the cowgirl's hand pat you closer and closer towards Celestia's hole while you heard the cowgirl, "But that ain't gonna save ya! I trained Celestia ta ignore all ya varmit's pleading and begging! and ya just bought yourself a closer view at Celestia's hole for the MONTH ya'll be spending together!" You were now practically kissing the hole of the giant horse pokemon!
"But ya know, I seen a lotta Tinies gettin' horseassed. And you, li'l varmit, make the best lookin' for time with Celestia! Who knows? Ya last the month on her tail, I may end up lettin' her KEEP ya!" The giantess above you laughed as she went back to ignoring you and nudged the Rapadash's sides with her heels. "Giddyup, Celestia!"