He allows himself to feel it all; the indecision, the crushing doubt, the dread, and the grief of having lost his family...somewhere. Each of these realizations knocks more and more wind from his sails, until finally there's jut him clinging to the bookshelves doing the only thing left for him to do: He breathes.

With each breath he comes back to himself, and finds that he's one step closer to center.
Somewhere...wherever his brother is, he's sure Tenzin is gloating.
The jerk.

Bumi laughs a dry laugh and continues his climb to the top of the bookshelf, where Aang is. With a huff he's clambering over the top, landing in a bit of a heap across from the boy who will someday be his father.

"I'm okay," he says reassuringly, though if it's for his benefit or Aang's is not entirely clear.