Dick Grayson: The first Robin who then went on to be Nightwing. During the events of the Knightfall Bruce Wayne tangled with Bane, who in the end broke his back leaving him crippled. After his first replacement was deemed unsuitable Dick took the mantle until Bruce healed. Grayson thought his time in the cape was over and he could return to being Nightwing. How wrong he was.
During the Batman RIP storyline in which Bruce Wayne was ‘killed’, Dick found himself taking up the mantle again. This time he aimed to be light hearted Batman leaving all the seriousness down to Damian. Bruce eventually returned and Grayson again returned to being Nightwing.
Jean Paul Valley: The replacement which didn’t work out. Valley found out one day he was in a long line of men subliminally programmed to become the hero of an ancient order and taking the guise of Arazel. After Bruce guided him away from the urge to kill he decided to keep him as a back up just in case something happened to him.
It’s a good thing he planned ahead. After Bane broke his back Valley was called up. Though things did not go well. After being doused with some of Scarecrows fear gas some of Valleys old Arazel programming altered his personality. Valley becomes ultra violent and begins to go on a aggressive campaign against crime.
He begins to re-design his Bat-suit to the point he’s wearing huge robotic armour. After shunning Robin and Alfred, Bruce finally returns and claims his mantle by luring Valley into the depths of the Bat-cave causing him to remove his armour leaving him vulnerable.
Damian Wayne: Prior to his untimely demise Damian decided to cheer his farther up. Luring Bruce onto a trip around the world to visit locations linked to his parents, Damian took up the Batman guise whilst he was away. Damian played the Batman guise like an over the top short Christian Bale branding out his violent brand of justice.
When Bruce returned Damian quietly hid the escapades which had happened in his absence.