Why No One Except Bruce Wayne Could Handle Being Batman
First let's establish his potential heirs from first to current: Dick Grayson, Jason Todd, Tim Drake, and Damian Wayne. Dick Grayson was Batman's first Robin and he is also known to be his prodigal son. Dick Grayson is the one whom Bruce is closest too and seems to care the most about even though he's hard on him. He is currently Nightwing. Jason Todd was Batman's first mistake, at least, what Batman feels was his mistake. Jason Todd was the second Robin, he was very different from Dick as he was much more impulsive and hard to control. Jason Todd was brutally beaten by the Joker with a crowbar and then left to die in a shed stocked with dynamite. Batman was too late to save him and he continues to blame himself. However, Jason was resurrected by Ra's Al Ghul and become The Red Hood. Tim Drake was the third Robin. He figured out Batman and Robin's identities and after Jason's death assumed the role of Robin. Unlike the other Robin's, Tim was not originally an orphan, however, after he becomes Robin, his mother died and his father was killed by Captain Boomerang. Tim becomes Red Robin and eventually leader of the Teen Titans. Finally, there is the current Robin: Damian Wayne. Damian is Bruce's actual, biological son, though all Robins are referred to be his sons. Damian is the son of Bruce Wayne and Talia Al Ghul. He was raised by his mother and the League of Assassins until this point where Talia hands him over to Bruce. Damian is very disconnected from the world and does not seem to feel remorse nor really understand the meaning of true justice, but he is making progress.
We'll start from bottom to top in who could take over as Batman and why they wouldn't be able to.
Damian is the least likely to be able to properly handle the Batman role. Not only is he far too young, but he does not understand what it is to be a hero, to be Batman. Damian is very intelligent and very skilled at engineering and building. He is also involved in the business at Wayne Enterprise alongside his father. However, Damian does not understand remorse. He kills criminals without a second thought because he feels that this is the only way to truly stop them. For Batman, this isn't justice. Killing those who kill make you just as bad as they are. To be Batman, you must be able to control yourself and to separate yourself from those who are bad. Damien is also very impatient. He often argues with Bruce about just going out and hunting down a villain when Bruce would rather take a day to heal and try to learn more about that person. Damian also makes decisions based on trying to prove himself to his father rather than think them out to the fullest. He constantly tries to fight with Dick and Tim as a way to establish himself as a superior Robin. He alsolashes out and acts on impulse rather than logic. This is shown especially during the Battle for the Cowl when, as a way to prove himself to Dick, he attacks Jason and almost gets himself killed.
Jason Todd is very close to Damian, but would be a slightly better choice because he does understand the importance of justice. But, like Damian, Jason kills people only with guns (or his knife). Jason also feels that ridding the world of the psychos and the criminals is the only real way to save it. Jason's skills lie in his detective ability. In Under the Red Hood he always seems to stay once step ahead of Batman in tracking down villains as well as already having a trap set up for them by the time Batman gets there. Jason is more of an anti-hero than a hero though. He also seems to be fueled by vengeance but not in the way Batman is. Jason clearly has a lot of emotional problems and lets those emotions get the best of him. A hero without a true cause is no hero. The emotional issues Jason carries with him are enough to make it virtually impossible for him to be Batman. During the Battle for the Cowl Jason actually begins to attempt to kill members of the “Bat-family”.
Tim is a good candidate, however, I just don't think he would be able to handle the strain. Tim is very smart in all aspects. He is a good detective and he is a flat out fast learner in pretty much any subject. But it seems to me Tim lacks the mental stamina to be Batman. Tim almost kills Captain Boomerang and when Batman “dies” in final crisis, Tim continues to be Red Robin but seems to stop caring about Gotham and only focus on finding Bruce. Though this is great dedication to his mentor, it is obvious that losses such as these are too great for Tim to handle. Being Batman means seclusion and the responsibility to do what is right for Gotham and if someone important dies, Batman must still go on. (Like when Bruce continued to be Batman even after Jason's death). Tim also has a brief falling-out with Bruce and again resorts to a form of seclusion to deal with it.
Dick Grayson is the best possible option for anyone who could be Batman (he even does so for a bit during the Battle for the Cowl). Dick is the “prodigal son”, he is a born leader and a strategist. However, Dick is very lighthearted. He constantly makes jokes and he has a personality anyone would love. But as we see with Bruce in every comic, being Batman is a mental strain and even the most positive people can be consumed by the dark the cowl brings. There is also the immense pressure Dick feels to live up to Bruce's expectations. Being the favorite is a good thing, but it also means Bruce expects more from Nightwing. Dick constantly struggles with his master's lack of approval and becoming Batman furthers that pressure. During his time as Batman, Dick's personality changes and he becomes as cold as Batman. He takes the cowl despite Bruce's will for him not to, he seeks Bruce's respect and praise and it drives him into negativity. Had Bruce not returned, I think Dick probably would have cracked under the pressure.
The pressure that comes with being Batman is one only Bruce can handle. Yes, Bruce can be cold, but it is only because he has to be. The things he has seen, the trials he has gone through, no person could actually stay sane, except Bruce. He is a diamond in the rough and his dedication to Gotham keeps him strong. During the Court of Owls he almost loses himself and he does temporarily go insane after his time spent in a never-ending maze. However, Bruce somehow has a mental capacity that surpasses all other comic book characters and he thinks himself out of insanity. Although Batman is a symbol and stands for more than just Bruce Wayne, Bruce is the only person that can dawn that symbol and take the consequences that come with it.