This one can be interpreted as friendship-love, or a crush, whichever suits you.
Disclaimer: I do not own Avatar the Last Airbender
Ty Lee liked to think that she could make anyone happy if she put her mind to it. She was bubbly, and she liked other people to be just as happy as her. Maybe that's why Mai was her bestest friend. She often found herself surrounded by people with dark auras and worked extra hard to make them happy.
When Zuko finally returned from his banishment, he seemed sadder than ever, even when he was with Mai again. He had always been a sad-faced boy, so Ty Lee hugged him. And maybe that day, his aura seemed a little brighter.