Chapter 3: After Toph wakes up from a nightmare, Zuko not only comforts her but also (despite being sore and desperate for sleep) joins her to sleep on the floor where she can see. Toph decides he's the best big brother ever and if Azula doesn't want him she's calling dibs.
Even if it's misplaced, the base's concern for the kids. Because in spite of their magic kung-fu, Toph and Zuko are still kids, and kids should have fun and mischief, not fight in a war.
Chapter 11, when the kids from Avatar finally meet up and have a group hug.