Nai's real weakness is not quite knowing what to do with all these different emotions he sees in people. What can he do when someone is sad, or angry? All he wants is to return the kindness others have shown to him. His inability to speak his thoughts clearly and efficiently hinders that desire at times, like now, so Korra's gratitude and embrace are a bit surprising.

"Downer...?" He eventually puts his hands on her arms and tries to peek at her. "You're welcome, Korra." At least he knows his manners. He smiles a little before hugging her properly, hoping this makes her feel better.