This is the end of the interlude, and Arc 4!
A little more context/elaboration? I think Danny and Cat spent quite a bit of time together while he was healing, and it gave him a chance to be an actual kid for a bit, since he'd already been with the military a while... The next time they saw each other would be as adults. Cat's town had been kinda decimated, and more and more people were leaving. She was looking for a way out herself. Danny sought her out specifically because the crew needed a physician. He explained she'd need to pretend to be a man. He probably expected her to have more of a problem with it than she did. It's never been something she's struggled with.