A new trailer for The Walking Dead: Dead City reveals how Negan (Jeffrey Dean Morgan) and Maggie (Lauren Cohan) find their way to Manhattan. The Walking Dead: Dead City is a spinoff and sequel to The Walking Dead, featuring Maggie and Negan heading to New York City to rescue Maggie's son Hershel (Logan Kim). Hershel has been captured by The Croat (Željko Ivanek), a mysterious figure within the Big Apple.
The Walking Dead series finale saw Maggie accept Negan's redemption, but told him that she would never be able to forgive him for killing Glenn in season 7. Negan was last seen nodding to Daryl before wandering off, presumably to settle down in one of the communities with his wife Annie. Maggie and Negan's final interaction indicates Maggie would never recruit Negan to help rescue Hershel unless it was absolutely necessary.
The character holding Negan's wanted poster in The Walking Dead: Dead City teaser seems to be Perlie Armstrong (Gaius Charles), a newcomer who appears to be hunting down Negan. This indicates some New Yorkers may already know who Negan is, which would explain why Maggie decides to take him to Manhattan with her. Perhaps The Croat and Negan have an unexplored history together that will explain why he decided to capture Hershel and what he truly wants.
While Morgan has teased Maggie and Negan's relationship won't be smooth sailing, the pair working together means they both have some significant stake in the rescue mission. Though Negan's role could be as simple as wanting to prove to Maggie that he's changed by saving Hershel's life. Even so, there's still plenty of mystery surrounding.