This article does contain spoilers for the final episode of The Winchesters season 1 and Supernatural season 15 ending, on The CW.
Fans have long voiced concern, due to the continuity not matching up with the supernatural timeline, as to not disrupt anything.
Many have theorized that the finale could involve characters losing their memories, to be able to somehow put the timeline back on track. As John was not meant to know about hunting and the Men of Letters, among other things this early. Now, this has finally been resolved to be something else.
Supernatural season 15 ending
It’s best to start explaining this from the final season 15 of Supernatural; Chuck/God was meddling with many universes in his power trip to control a story that suits him, and Sam (Jared Padelecki) and Dean (Jensen Ackles) were able to put a stop to this, with the help of Jack (Alexander Calvert).
Almost everything worked out well; Chuck was now human and Jack became the new God. Although, the brothers continued to hunt, until Dean Winchester was suddenly killed in a barn.
Dean went on a roadtrip to heaven, however before he would actually reach his destination, he took a slight detour through the multiverse as a ghost; in order to find a timeline where his parents could potentially lead a happier life.
During that detour gap, Sam Winchester would still be living out his life, before he reaches that bridge in Heaven.
The Winchesters’ universe
He found a timeline where Chuck’s evil monsters called the ‘Akrida’ were still running rampant, and they could eventually come back to the main Supernatural timeline; to put his family in danger as well.
Dean chose to give this different timeline a nudge where Mary (Meg Donnelly) and John (Drake Rodger) are in The Winchesters series; by giving them clues to change things.
There are also other surprise characters who show up throughout the season to look out for.
The way this first season was wrapped up, it seems like there might not be a second season. Dean gave them the secrets to not end up like his own timeline. Both Mary and John then went on a long roadtrip to enjoy their lives.