Supernatural canon problem that’s been at the show's forefront since the pilot. The Winchesters episode 8, "Hang on to your Life," brought back Richard Speight Jr. as Loki the Trickster, but also answered the question of who gave John the letter about his father in the pilot. The Winchesters' canon previously had some inconsistencies when aligned with its predecessor, Supernatural.
There were contradictions regarding when John Winchester and Mary Campbell became a couple and how John started hunting. It was previously believed that John only started hunting after the death of Mary in the Supernatural pilot. Additionally, it was established in the early seasons of Supernatural how to kill Loki, but The Winchesters episode 8 changed the lore. These inconsistencies were starting to feel deliberate and not just because of the Akrida that John, Mary, and the company were fighting.
Dean's Letter Can Explain The Winchesters' Continuity Problems
Dean Winchester (Jensen Ackles) narrated each episode of The Winchesters and even appeared in the pilot. He was also seen driving his now-iconic car from the first few seasons of his and Sam's show, the 1967 Chevy Impala from Supernatural. At the end of "Hang on to your Life," it was suggested that Dean was the person who gave John the letter when he came home from Vietnam. The letter led to John meeting Mary at the Men of Letters base in Lawrence, Kansas.
Because Dean, who was from the future, delivered the letter to his father, he subsequently changed the canon. Everything that happened before Dean transferred that letter was Supernatural canon, but everything after was a new branch of history. It became a new canon. It’s unclear why or how Dean did this, if he is alive since he died in the Supernatural series finale, or if The Winchesters takes place in a different universe. This could vindicate the canon and lore inconsistencies in one quick, in-universe explanation.
How The Winchesters' New History Would Change Supernatural
The Winchesters now reside in a different canon than the one fans would recognize from Supernatural. This could mean that the Sam and Dean Winchester that came over from a different reality in Supernatural season 15 could be the result of The Winchesters timeline. It may even mean that Dean and Sam were born earlier or that Samuel and Deanna Campbell might live to see John and Mary get married. As the new God, Jack from Supernatural may have sent Dean to this different universe to fight The Winchesters' big bad in the Akrida and save the human race.
It's unclear what role Jensen Ackles’ Dean Winchester will have in The Winchesters' remaining episodes, but hopefully, he will be able to clear up these lore inconsistencies. Additionally, Dean’s appearance may mean more appearances from other Supernatural characters like Sam, Castiel, or Jack. There are only five episodes of The Winchesters left to air this season. With the suggestion that Dean sent the letter and created an alternate timeline, the show can potentially wrap up its story satisfyingly, which will justify its Supernatural canon problem.