What about "family" did Maniac Magee love in Maniac Magee?

Maniac wants to belong somewhere, with people who love him and a real address. 

Maniac lost his family when his parents died.  He was shipped off to relatives, but they were horrible people who ignored him and he ran away.  Since then, all Maniac did was search for a new family.  He ran to Two Mills, and there he met Amanda Beale.  The Beales took him in, but there was one problem.  They were black...

Maniac wants to belong somewhere, with people who love him and a real address. 

Maniac lost his family when his parents died.  He was shipped off to relatives, but they were horrible people who ignored him and he ran away.  Since then, all Maniac did was search for a new family.  He ran to Two Mills, and there he met Amanda Beale.  The Beales took him in, but there was one problem.  They were black and he was white.

More than anything, Maniac wanted to hug Amanda and tell her it was okay. He wanted to go inside, be with his family, in his house, his room, behind his window. But that wasn't the right thing. The right thing was to make sure the Beales didn't get hurt anymore. He couldn't keep letting them pay such a price for him. (Ch. 21)

Maniac loved everything about being a part of a family.  When he had to leave the Beales, he was heartbroken.  He felt that he was a member of the family even if he was white and they were black. 

It did not matter to Maniac that the Beales were black.  It did not matter to the Beales that Maniac was white.  However, the neighborhood was not so understanding.  In Two Mills, you lived on West End if you were white and the East End if you were black.  No one was prepared to change this.

When Maniac meets Grayson, he is shocked that Maniac came from the East End.  He just does not know that much about black families.  Yet Maniac tells him that the Beales were indeed his family, regardless of race. 

"Mrs. Beale. Do you know the Beales? Of seven twenty-eight Sycamore Street?"

The old man shook his head.

"Well, they were my family. I had a mother and father and a little brother and sister and a sister my age and a dog. My own room, too." (Ch. 24) 

Maniac has a family with Grayson.  It is certainly not a traditional family.  However, Grayson cares about Maniac and Maniac cares about him.  Maniac teaches Grayson how to read, and they have a good time until Grayson unexpectedly dies.  Maniac decides that he should go back to the Beales, because even if it is unpopular they really are his family.