Batman's vanishing trick has a rather painful explanation
Batman is one of DC Comics' iconic and most popular superheroes. The character has a wide range of skills in his arsenal, ranging from high-intelligence and detective skills to his mastery of multiple martial arts as well as stealth and deception.
However, there is one skill that the superhero is most famous for -- his ability to suddenly disappear from his allies or enemies whenever they are in the middle of sentences while saying something.
Batman's this habit has often annoyed the likes of Commissioner Gordon and Green Arrow, but it is unknown as to why he does it. This vanishing ability of the Dark Knight has even been termed a superpower by fans and readers because of how sudden and abrupt it is. He has even taught this trick to his partners Nightwing, Robin, and Batgirl.
However, there is a heartbreaking explanation as to why he does it, which was revealed in issue #25 of the 2000 comic book Legends of the Dark Knight by Greg Rucka and Rick Burchett.
Batman performs his signature vanishing trick because of his inability to say "goodbye"
In the comic, set after the storyline No Man's Land, Batman and Commissioner Gordon are seen arguing over the nature of their relationship. The latter questions Batman on whether he ever considered him a true friend. He further suspects that Dark Knight was only using him to obtain classified information from the police, while Gordon himself was laughed at by his colleagues for not being able to perform his duties as a police officer.
In the heat of their argument, Gordon brings up the fact that friends tell each other their plans and feelings and that they do not walk away from one another in the middle of sentences. To this, Batman finally admits the reason as to why he often disappears on the commissioner and it is because he cannot say goodbye.
The Dark Knight's inability to say goodbye is connected to his fear of loss and how he developed an aversion to that concept ever since he lost his parents, Thomas and Martha Wayne, to a gunshot, an event that left him traumatized.
This also explains why he is distrustful and detached from even his closest allies such as Robin, Superman and other heroes, with the only possible exception being his butler Alfred Pennyworth, and keeping them at arm's length as he does not want to experience loss ever again following the deaths of his parents.
It also explains his "no kill" rule and how he goes out of his way to save criminals, even ones that are undeserving, like the Joker, because he does not want them to experience any form of loss like he has or does not want to see another person die in front of him.
Thus, although Batman's vanishing trick is rather rude and disrespectful, it is nonetheless still understandable, owing to him fearing losing someone due to having lost many loved ones in his life, such as his parents and his protege and second Robin, Jason Todd.
Batman's other famed skills
The Dark Knight, aside from his famed vanishing trick, has also mastered the art of psychology and fear to a great degree that he is capable of terrifying normal criminals and sometimes even the police.
In fact, his mastery of fear is so great that the comic book Batman: Reptilian by Garth Ennis acknowledges how the Dark Knight makes his presence and intimidation known even in places where he is not physically present, making crooks believe that he could appear anywhere at any moment in time.
He is also shown to be very meticulous and calculating as well as being prepared for the worst outcomes in any scenario. This is shown when he often carries a piece of Kryptonite with him anywhere he goes in the event Superman loses control. The Dark Knight even once developed plans to take on the Justice League in case they go rogue, as seen in the comic book storyline JLA: Tower of Babel.