Borderlands: The Pre-Sequel is getting a bonus mission which will help explain the presence of Handsome Jack in Tales from the Borderlands.
Early Tales from the Borderlands trailers teased the return of Handsome Jack in some form, which was a little confusing, as Gearbox kept saying that the villain of Borderlands 2 would not be returning from the dead.
I don't want to spoil Jack's role in Tales from the Borderlands, although if you watched the trailers you probably guessed already, so I won't go into more detail. But: Gearbox and 2K Australia have decided to fill in the backstory a little with a new mission for Borderlands: The Pre-Sequel.
According to the Gearbox blog, which you shouldn't click through to if you're trying to avoid spoilers, the mission will be included in the new DLC drop, which is called Ultimate Vault Hunter Upgrade Pack: The Holodome Onslaught.