Here's a list of a few charactes you could look at using.

Dick Grayson/Nightwing
Jason Todd/Red Hood
Timothy Drake/Red Robin
Damian Wayne/Robin
Barbara Gordon/Batgirl/Oracle
Katherine Kane/Batwoman – Claimed
Stephanie Brown/Batgirl/Spoiler
Cassandra Cain/Black Bat
Lucas Fox/Batwing
Helena Bartinelli/Huntres
Talon - Claimed