Warning: Spoilers for Batman Beyond #49 by Dan Jurgens and Paul Pelletier
As Amanda Waller once told an adult Terry McGinnis, you can't be Batman without tragedy. This proved true when the murder of Terry's father Warren McGinnis was the primary motivation for Terry to assume the mantle of DC Comics rewrite his origin story to ensure that he would always become Batman.
In the to succeed him as Batman, under his supervision.
In the 'Canceled by Yesterday' storyline, Terry ends up saving a child who turns out to be a young version of his father Warren. While Batman and Booster fight the villain Blanque, a powerful telekinetic who is supposedly responsible for everything, Terry struggles to protect his father while not revealing what he knows of their future.
In such a short amount of time, Dan Jurgens uses one of his best-known characters to present one of the hardest challenges about time travel - wanting to use your knowledge of the future to change your past for the better. Although Terry's intentions are good and understandable, his obligation as a hero has him rise above any self-centered desires and save the day. As the surrounding fires act as a smokescreen, he helps Booster defeat Blanque. After saying goodbye to his father, Terry returns to a changed timeline where Bruce is fine and readers learn the entire situation was a ruse with a specific purpose.
As Bruce explains to an older and far more responsible Booster Gold, the entire situation had to be concocted so that Terry would go back in time and meet his father. The positive experience taught Warren about the importance of doing the right thing regardless of its personal cost, something he confided in his journals, which later ended up in Bruce Wayne's possession. Dan Jurgens rewrote it so that without Warren meeting his future son, he wouldn't have had the courage to investigate his findings at Wayne-Powers. Terry McGinnis was always destined to become Batman Beyond and to change that would now require literally changing time.
