Flint was a teenager on Belderone who became Vader’s Apprentice in the first volume of Marvel Star Wars comics in 1983.
Flint and his friend Barney wanted to join the Rebellion when they landed to establish a secondary base near Kulthis, in between the events of Empire Strikes Back and Return of the Jedi.
Flint was set up as a counterpart to Luke, his dad was a Jedi before the Empire’s purge.
Flint and Barney were with the rebels when the Empire attacked Belderone and Luke left for reinforcements. Imperial walkers destroyed the port and killed Flint’s mother Zara.
Vader was there to tell him Luke and the Rebels were to blame. Barney was injured in the attack but joined the Rebellion and left the planet.
About a year later, in Star Wars #92, Flint appeared in the comics as Vader’s successor after the events of Return of the Jedi.
Barney managed to convince him to break with the Empire.