Timothy Fox is the eldest son of Lucius Fox who in the pre-Crisis DC Universe did not get along with his father because of Tim's affiliation with Ron Watkins' gang. Ron Watkins worked with Gregorian Falstaff and they together tried to fabricate evidence in order to make Bruce Wayne look like a slumlord. Because Lucius worked closely with Bruce Wayne he had a falling out with son. Later Tim realized what Watkins was trying to achieve and apologized to his father but knew that it will take a while for them to be able to talk again.
After these events Crisis on Infinite Earths happened and Tim was never to be seen again until Dark Nights : Death Metal concluded and the next line-wide DC event, called Future State, was announced.
In the Future State timeline Timothy Fox had allegedly been in a car accident which was caused by him, got estranged to his family and left to join the military academy. After makin an abrupt return to Gotham City at a time when Gotham was a police state under the protection of the Magistrate, who had hunted down the Gotham City vigilantes, including the original Batman - Bruce Wayne. After the apparent killing of Bruce Wayne, Tim, who was now going by the name of Jace, would succeed Bruce and take up the mantle of Batman.
Timothy Fox was created by Len Wein and Irv Novick and first appeared in Batman #313 - Two For The Money!
Timothy Fox first appeared in the main Batman title as the eldest and at the time only son of Lucius Fox. He partnered with a guy named Ron Watkins who was working in partnership with Gregorian Falstaff. Together they were trying to fabricate and manipulate evidence in order to make Bruce Wayne look like a slumlord. While Tim was working with these people, his father disagreed with his views because he worked with Bruce Wayne. The two of them had a falling off until Tim realized his mistake and apologized. However, he understood the significance of his stance and knew that it would take some time while the wounds heal.
Even though the altering event known as Crisis on Infinite Earths happened, the story of Tim remained largely intact, but he wasn't to be seen until the modern event Dark Nights: Death Metal.
The Next Batman and Future State
Timothy Fox made an appearance in the newly created timeline known as Future State. In this timeline, Tim goes by the name of Jace after he had a falling off with his family and took a leave from Gotham City to attend to military school. When he returned to Gotham City, a group known as the Magistrate had taken over the protection of the city. Policing the city they hunted down all the known vigilantes in Gotham and even Gotham City's protector - Bruce Wayne. After the alleged death of Bruce Wayne, Jace took the mantle and carried on with the protection of Gotham and lead the battle against the Magistrate.
After the brief mini he had during Future State, John Ridley continued the development of the character and introducing him back to the ranks of Gotham into the main timeline. During the mini-series The Next Batman: Second Son, John Ridley explored more of the origins of the character into the now Prime Earth - Earth 0. As a kid Tim didn't get too much attention from his father, who was occupied at his job at Wayne Enterprises as a COO. Tim didn't mind the lack of attention as his father provided for him and Tim could live lavashly and act like a playboy. However, on his seventeenth birthday party, after failing to seduce a girl he was interested in, he left rashly his party. The angered Tim drove off with his car while talking over the phone with a girl. While talking and getting distracted he didn't see a guy crossing the street and hit him with his car. In a state of panic he fled the crime scene even though the guy he hit begged him to help him. In order to cover up the whole story, Lucius hired an expensive team of lawyers who dug out information for the victim and painted him in the media as the actual offender at the time.
Tim disapproved of his father's methods, who in order to avoid arguing with his son sent him to the Sanford Millitary Academy where he graduated and met some of his acquaintances - Vol and Hadiyah.
Tim graduated from the Academy but knew the skills he had learned weren't enough and continued to work with various mentors after that. While studying and continuing to be away from Gotham, Tim decided to change up his name and started going by the name of Jace. With this new name and skills under his belt, he decided to act as a covert operative along his fellow student Vol and targeted various underworld figures that were untouched by the law.
On his last mission before returning to Gotham, Jace and Vol, who acted as his field operative, decided to go after Tyler Arkadine in Vietnam. The attempt was to stop Arkadine's trafficking ring. However, when the mission went awry Jace found Grifter who was there on behalf of Lucius Fox, so he can get Jace back to Gotham.
When Tim, now going as Jace, returned to Gotham he saw that nothing much had changed - his father was still emotionally distant, his mother saw him as a disappointment and had a grudge against all vigilantes and his brother Luke, Batwing, still couldn't forgive him about his past mistakes. Only his two sisters were trying to connect with him and renew the normal dynamic of their family. Howevr, later on an incident happened with Tim's older sister - Tamara, who was poisoned by Ratcatcher, she went into a coma and the coldness between the family members continued.
Tim continued his mission to stop Tyler Arkadine ending up against one of his hired assassins, an Irish female assassin named Eabha O'Roark. He took her down with the help of one of his mentors - Katana. In order for Tim to continue his vigilante mission and have access to better tech, so his partner Vol can continue helping him, he started working alongside his father. One day he came across a hidden basement within the Wayne Enterprises building where he came across the Bat tech that was being supplied to Bruce Wayne by Lucius Fox.