I'd heavily play on the Mob angle with Tony Zucco. And Dick's origin as Robin would be a slowburn over the course of a movie. He probably doesn't wear a proper suit till the last act, if not the last scene.
Age-wise, Dick would be around 15-16. Since Pattison's Bruce is probably in his late 20's, or not much older than 30, it'd be less a father-son relationship and more of an older brother dynamic.
A major aspect will be that Dick starts investigating his parent's murder on his own, actively putting his life in danger. Bruce repeatedly tries to stop him, but fails. He realizes that he has no choice but to take Dick on as a partner to ensure that the boy doesn't get himself killed.
I'd have Dick wear his circus costume at one point, which looks kinda Robin-like. The final suit I think should be a more armored up, darker version of Tim's red and black suit. Or something like the Titans Robin suit.