First teased a while back, it was revealed Sunday onTalking Deadwhich character will be crossing over between AMC’sThe Walking Deadand its spinoff companion seriesFear the Walking Dead. While some thought maybe this “crossover” would simply be one character popping over to the other show for one episode, this is actually a full changing of the guard.Lennie James, who plays Morgan onThe Walking Dead, will depart the flagship series by the end of the show’s current eighth season to join the cast ofFear the Walking Dead. He’ll make his debut in Season 4 of the spinoff series, airing in 2018.

James made hisThe Walking Deaddebut all the way back in the pilot, playing one of the first characters that protagonist Rick Grimes (Andrew Lincoln) encounters after waking up in the abandoned/zombie-infested hospital. He returned for one episode in the show’s third season for a surprise appearance, popping up again for two more episodes in Season 4 before becoming a series regular in Season 5.

It’s unclear how Morgan’s exit will be handled. He could conceivably be killed off sinceFear the Walking Deadtakes place in a different, earlier timeline thanThe Walking Dead, so the idea presumably is to fill in the gaps of Morgan’s story.

After debuting to pretty high numbers,Fear the Walking Dead’s ratings entered a downslope in Season 2 before resting around 2.3 million viewers towards the end of its third season. AMC no doubt hopes this crossover brings in more eyeballs to the spinoff series, but the flagship show isn’t doing so hot either. Once untouchable,The Walking Dead’s numbers started to decline in Season 7 and have somewhat plummeted in the current eighth season. The show is far from the danger zone, but in a sign that no series is immortal (unless your name isNCIS), it’s now a far cry from its heydey as the highest-rated show on TV by a country mile.

The Walking DeadshowrunnerScott M. Gimplepromises there’s still “a lot of story” left for Morgan on the main series, adding “Morgan’s arc onThe Walking DeadSeason 8 positioned him for the story onFear. It was also important to seeFear’s world and characters through new yet familiar eyes.”

The Walking DeadSeason 8 is currently airing on AMC.