"Survival Sunday," the night in which Morgan (Lennie James) crossed over from the Season 8 finale of The Walking Dead to the Season 4 premiere of the creatively rebooted spin-off Fear the Walking Dead, went off mostly without a hitch. But some folks were a little confused by the timelines.

Some Walking Dead fans on Twitter didn't understand how exactly Morgan ended up on Fear the Walking Dead, since Fear started before the events of The Walking Dead — Season 3 of Fear probably took place sometime around the time The Walking Dead arrived at Hershel's farm way back in Season 2 — and Fear previously had no connection to the mothership show.

Here's what happened: Originally there was no plan to ever have the shows cross over. But before Season 3 of Fear premiered, AMC announced that co-creator Dave Erickson would be leaving the show at the end of the season and new showrunners Andrew Chambliss and Ian Goldberg would be taking over for Season 4. It was an opportunity to fix some of the show's problems, and Chambliss and Goldberg worked together with then-Walking Dead showrunner Scott Gimple to revamp the series and bring it closer to the mothership for this current season.

The way they decided to do this was by having Morgan switch shows. To do that, they would have to move Fear the Walking Dead's timeline up a couple of years to meet The Walking Dead. But since there are still lingering plot threads from Season 3 that have to be addressed, Season 4 of Fear is going to unfold over multiple timelines.

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Those timelines are:

• Morgan's story, which is happening a few months after the events of The Walking Dead's Season 8 finale and includes the present-day versions of the original cast, minus Madison (Kim Dickens).

• The story of how the original cast went from living peacefully at a baseball stadium to becoming the roadside bandits who met Morgan, which will start about a year after the events of Fear's Season 3 finale.

• And presumably (this one has not been seen in the first two episodes sent to critics) the year between the Season 3 finale and where the original cast's story picks up, which will fill in the rest of the time jump that kicks off Season 4.

There may be other side-stories, too, that fill in how new characters like John Dorie (Garret Dillahunt), Naomi (Jenna Elfman) and Althea (Maggie Grace) ended up where they are.

It's a little confusing, but it's pretty comprehensible. If you keep watching Fear the Walking Dead, you'll get it.

Fear the Walking Dead airs Sundays at 9/8c on AMC.