A Corner of the Universe

Hattie suddenly discovers she has an uncle
she's never heard about when Adam returns
home. But Adam is not just any regular
uncle; Adam, she is told, is mentally ill.
Adam is loud and enthusiastic and repeats
things over and over and quotes continually
from I Love Lucy. And, in addition, Adam
lifts the corners of Hattie's universe.
Recommended.

This was one of my absolute favourite books when I was younger, but I sold off my paperback ages ago (along with Holes). Kind of regret it.