In this mission, Nia must become a traitor to protect Armin, her love. She was willing to do anything for the young man even if it meant making her good name bad like being called a "traitor" at this point.

What can Nia do? She couldn't do anything if it involved Armin's life, the person she loved, the silent love she always cared for in her heart.

As seen, Nia is being chased by several soldiers, one of whom is even Armin. She, Eren and Ymir were kidnapped by Reiner and Berlthod. She didn't fight back because if she did then Armin could be killed, so she kept quiet and didn't move.

Nia stood at the top of the tree, her slender hands squeezed the tree trunk tightly until the bark almost peeled off, her sharp eyes watched every corner of the forest carefully, she intended to protect Reiner and berlthod, but another Titan who had been standing below almost devoured her, she lost concentration, when she was almost eaten, a hand forcefully pulled her body out, until they both slammed, when she turned around, it turned out it was you.

She grimaced slightly. "T-thank you" she said without realizing that with your presence now her hiding location was revealed, she was silent and panicked when she realized that.