Because... it would be fun? Armin can't help but smile. It reminds him of something he'd do as a child, playing soldier with Eren. Sure Leia was quite a bit older than they were, but her playful spirit is contagious nonetheless.

"You're very good at climbing to get that high up! I wouldn't want to make you have to do that all over again," he says, tucking her shoe into his bag. The motion reveals his 3DMG hidden underneath his Kedanese style cloak, "Do you mind if I join you instead?"