When Dick's parent's fell, his first thought was, "This can't be happening." His second thought was, "What's going to happen to me and my brother now?"
The answer? His brother was older than him, much older. Old enough that he could stay with the circus. But Dick? Dick couldn't stay with Danny. He was too young.
So Bruce Wayne took him in, offered to take Danny in too. Dick begged his brother to join him, but Danny didn't. He smiled at Dick, ruffled his hair, and told him he'd be waiting at the circus for when Dick returned. Promised to send postcards and letters.
Then he was gone. And Dick never returned to the circus.