[Alluka feels weighed down from behind, her wings a lot heavier than expected as they trail behind her. As soon as he confirms they're butterfly wings, she positively glows with the enthusiasm of a little girl indulging in all her wildest fantasies.]

I'm a fairy, Oniichan! I knew I should've worn this outfit today!

[She tries to move her wings. They twitch slightly but they're not ready to move yet. As Killua said, they're still new and need to harden so they're resilient enough to capture the flowing wind.]

Aww, I guess I can't fly yet, though..can you?