Yeah, SHE'S the one Katara considers a mother figure, and she'd not letting anyone know that, least of all Marco. After learning all that happened with the Yeerk, Katara is intent on helping Eva however she can, and even lending a hand where no one asked. The latest thing with Marco hurt, but Katara was more focused on stopping Eva from going into the brig, but more, not letting anything control her mind again.

Eva gives her good advice and is able to comfort Katara even when she isn't her usual sunny self. That means a lot, and thought she'll only keep it to herself, she cares about Eva quite a lot.