A somewhat dark thought runs through your mind: you don't HAVE to turn anyone back. And with the way Devin is acting in Jessica's body...you can't really say you dislike it.
"...Nah," you say.
Devin freezes in place, and blinks at you slowly. "Uh...what?"
"Honestly, Dev? I think you know I like Jess...like, a lot. But when you've got her body, you..." You clear your throat. "I like you better like this."
"W-wait, what happened to 'holding Jess's body hostage?' And what are you gonna do about Jess, for that matter?"
"I dunno. Figure it out later, I guess," you say with a shrug.
"...Dude..." says Devin, stunned. "That's...a little messed up."
"Ah, c'mon, you know I wouldn't do anything terrible to her. I can get her whatever other body she wants. I just...happen to like you in hers."
"Thanks...?" says Devin, an uncertain tone in his voice.
"So, question, then: if I broke up with Jess, would you go out with me?"
"Uh!" Devin replies, jumping. "Not in that body, no! At least get back in your own first! And besides, I'm still me in here! Although, I guess it'd be a shame to have a female body and not at least try it with...oh god."
"Eh?"
"...Am I bi?"
"Wha--I don't know!"
"I mean, I definitely considered it just now, but--"
"Focus, Dev, please," you interrupt.
"What?" asks Devin with a shrug. "Like I said, not with that body. Going out with myself would be weird. Beyond that...I'd try it, I guess? I don't know, dude, you just asked me the weirdest question. Look, if you're not gonna swap us back, we should probably get to our next classes, huh?"
"...Shit, you're right. Alright, look, I'll see you later, then!" With that, you wave and walk away, leaving your best friend in your girlfriend's body, with her stuck in yours.
That's...more than a little messed up, you realize as you round the corner towards Devin's next class - your next class, and there's not much you can really do to change that at this point. And it's probably a little late to back out. Well...Jess will understand, you hope. And if not, there's not much she can do other than break up with you, which really just frees you up to keep going out with her body. You wonder, though - should you explain this situation to her? Or just surprise her by swapping back into your normal body? That would require you, as Devin, to kiss your body, which could be awkward. Maybe you should swap with another girl first. Then you wouldn't HAVE to involve Jess at all, although that might qualify as stranding her in your original body.