I imagine that if Bruce's parents had never been killed Batman may have manifested as a character Bruce pretended to be when he was a kid.

As for Robin- if the Waynes never died then I guess they could have had another kid, so here's little Richard Wayne in his Robin onesie. And, of course, Bruce has got to have a dog, so here's Ace the Bathound (Batpup?) to round out the group.
Then Alfred put them all in the Batvan and took them to Gotham Central Park.
In hindsight, after making everyone younger, I probably should have given Alfred a full head of hair... Oh well, sorry Al.
And here's a sepia tone "photograph" of the group... because apparently Bruce was a kid in the 1800's.