There were two missing halters, but the one she took for sure was the halter of... champion stud! He remembered boss talking about that one.
He remembers his boss talking about it: "Once you put it on, you have to become the champion and score with another! Otherwise, you'll eat hay for the rest of your life" he reminds bosses words. He thought it was some kind of stupid anecdote or proverb about acting quickly or living in the shadow. But it seems he was talking very literally about the halter.
He takes a quick look at the horse, still lying on the floor, trying to figure out how new legs work. Jessica was experiencing the rush of new hormones and senses, causing dizziness. He goes again to Jessica's head "oh, I think I know what's going on here..." he says with a cold tone. It doesn't mean good news.
The horse was trying to stand up, Alex tried to help. Thankfully the ground was rough enough to not slip, the horse also used a wall to keep balance. "No fucking way... he was telling truth..." he says examining the horse, then chuckles noticing something. Jessica became a stallion!
She or rather now he looks at Alex trying to figure out what's going on, what's so funny, when she felt some coldness in the area she didn't have any limb, beneath the stomach. He lowers his head and notices a stallion hood between his legs and whinnies terrified, then looks at Alex puzzled.
"Yhm.. yes, it is what you think it is... you are a stallion" explains the situation. The stallion lifts one of the forelegs and tried to touch it, or even push it back! Jessica wasn't the girl that jumps into bed at first date, actually, she was waiting for 'that one. "Easy, easy!" says grabbing his leg and try to put it down on the ground. "Just.. try to not think about it, it will... shrink back." says feeling disgusted, trying to teach his former female friend about male anatomy and reactions.
"Calm down... Okay, sorry!" apologizes, as the horse again burst in panic, like saying "calm down? I'm fucking horse, I won't calm down!", but then sees acting like this won't happen. "I know this must be... embarrassing... I can't say how you feel..." says calmly looking around. Finally, he found a horse rug. "This should help", then puts it on the horse, covering its torso and... that dangling organ, at least partially.
Jessica tries to calm down, slowly getting used to new senses. "The halter you put on is called 'Halter of champion stud'" explains. "Boss told me... that once you put it on, there is no escape. You must become champion and... score with another?" says as he remembered it. Jessica after few moments knew what it means. She, or rather he now... must win some championships to gain the title, then 'score': mount a mare. Jessica whinnies now understanding the fate that awaits the former girl.
After few moments Alex turns red, as he gets it too. "Oh fuck.. I mean.. I'm sorry! Looks like hard times await us". Jessica snorts at the word 'hard' again. Alex sighs and pats the stallion's neck "Boss will help us, he's a good man...". Yeah, he was often windy, frivolous, but would never harm anyone. And horses loved them.
Soon they noticed a former empty stall, the one boss said that must remain empty 'for some reasons', fills with hay and a label on doors appear: "JASPER". The stallion notices it and slowly and carefully placing his legs on the ground walks toward it. It smells like home for him. "That's new... Jasper?" Alex asks the former girl. Horse snorts and steps inside to look around. This stall was completely empty a few minutes ago!
"So... the halter renamed you to Jasper, I guess" concludes. "And this will be your new home"