An underutilised idea or au or whatever is jack drake never dying and tim staying as a member of the batfam but not the wayne family. I really loved the arc of tim quiting because bruce was acting crazy out of line. The possibility of not being able to stay in contact because their relationships foundation was robin and batman. Everything else they bonded over was just a result of that and couldn't have been possible without vigilantism as a common denominator. Even when they start viewing each other as more than partners and start playing into father son rolls you can't escape tim being robin.
Also having bruce feeling like he's spoiling or demantling a happy family/ what he misses most (even though the drakes have very obvious problems) would be interesting inner turmoil. Making tim Bruce's son was very understandable but the what ifs keep me up at night. And in the long run it would make for a great tim retirement comic. Or death comic or whatever...