I have a request to add to the pile.
What about Innes, Gerik, and Tethys in their joining chapter in Eirika's route in Sacred Stones. They've been fighting all day trying to hold their position, but that's not the only thing they've been holding. It was easier to ignore earlier but as the fighting drags on they all start to feel the pressure on their bladders.
They regroup in the fort to rest and relieve themselves. Problem is, the fort doesn't have those facilities available. So with enemies closing in and bladders full, it's back out to fight.
Marisa is there as a recruitable enemy and she's in the same situation. The attack has been going on since morning and she hasn't been relieved to 'relieve herself'. She tries to hide it behind a detached attitude but everyone who talks to her, enemy or ally, can see it clear as day.
If a character wets themself in the middle of the battle they get a stat boost/promotion like Hilda in the first request, but everyone who makes it to the end of the chapter without losing control gets a scene where they frantically look for somewhere private to drop trow. And maybe they even find one in time.