WARNING: The following article contains spoilers for The Walking Dead Season 9 episode "Evolution," which premiered Sunday on AMC.

The Walking Dead aired its midseason finale introduced an enigmatic and terrifying new enemy. However, as compelling as that storyline is, there are still a handful of rather pressing questions that have been raised by the first half of the season, but remain far from answered.

Here's what the second half of the season still has to explain, in addition to bringing Jesus' killer to justice.

WHY IS GABRIEL RESPONSIBLE FOR NEGAN?

At the beginning of the season, it looked as if Negan’s incarceration was something that, at the very least, Alexandria had agreed upon. Both Michonne and Rick met with him, and he was guarded by several people on rotation. But in “Evolution,” Gabriel revealed he couldn’t go look for or help Rosita because “someone” had to stay behind and watch after Negan. Why is Gabriel the only person responsible for Negan, instead of the entire community standing behind his incarceration as an example of the “new world” Rick wanted to build?

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It seems likely whatever happened between "What Comes After" and now that broke apart the communities also affected Negan’s imprisonment (or at least everyone’s opinion about it). It would make sense that Gabriel would be someone who would stand on principle to keep Negan alive if community outrage reached a boiling point. Negan’s spared life always seemed to hang in the balance, considering the remaining bitterness inspired by his depraved deeds as Savior leader. It’s possible Gabriel made some kind of deal to take sole responsibility for Negan during the six-year time jump, when those in power decided the man wasn’t worth the resources necessary to keep him imprisoned. That said, he’s not imprisoned any longer …

WHERE'S NEGAN?

Negan not only survived the six-year time jump, he seems to be thriving. His confrontation with Maggie in "What Comes After" revealed the depths of desperation his incarceration had dragged him to, but the communities refusal to let him die has clearly resulted in his acceptance of life, regardless of what form it takes. He’s created some kind of warped friendship with Judith, and “Evolution” revealed that he and Gabriel have established a similarly warped therapeutic relationship that’s an evolution of their initial meeting in Season 8's "The Big Scary U." Gabriel’s moved on from Negan’s confessor to something more rehabilitative. Early in the episode, the two work through a guided meditation seemingly designed to help Negan deal with his incarceration. While both grow weary of the exercise after a short while, it’s clear the relationship is productive in some capacity, even if that’s in fits and starts.

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But at the end of the day, Negan is still Negan. Despite that he clearly respects Gabriel and is invested in their work to some degree, that doesn’t stop him from taunting the priest about having to empty a prisoner’s bedpan. But after learning about Rosita’s injuries, Gabriel’s patience has run out and he stalks out of his session with the former Savior leader … forgetting to lock the cell door. After Negan accidentally bounces his tennis ball outside his cell, he notices the door is unlocked, and it doesn’t take him long to walk out with a smile on his face. So where’s he going?

He doesn’t have any loyal followers left to galvanize and the Sanctuary’s a ruin. Plus, he wouldn’t get very far on foot before Alexandria noticed he was missing. It’s possible this new enemy might occupy everyone long enough to allow him to get pretty far away, but it’s important to remember that Negan is not a man who likes scavenging to get by – as restrictive as a prison cell might be, it’s probably paradise compared to what Magna’s group has had to deal with. Honestly, we wouldn’t be surprised if Negan took a nice long walk and put himself back in captivity before anyone noticed he was gone.

WHAT BROKE APART THE COMMUNITIES?

The details of what’s changed in the six years since Rick’s apparent death have been slow to emerge, but one thing was clear almost immediately: The once closely tied communities of Alexandria, the Hilltop, the Kingdom and Oceanside are now inexplicably splintered. There’s clearly animosity between the leadership of Alexandria and Hilltop, the Kingdom is unsuccessfully trying to play peacemaker, and Oceanside has been conspicuously absent. So what happened?

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We can’t say much that’s definitive, but there are a few major clues we do have. In the past two episodes, both Michonne and Negan have voiced warnings about outside influence – Negan to Judith, and Michonne to literally anyone who will listen. The idea of welcoming anyone looking for a better life in order to build a “new world” seems to have backfired at some point. It’s possible the communities embraced a group of individuals who proceeded to try and take advantage of what they’d built, or perhaps take control of it altogether. Goodness knows that The Walking Dead has made it clear more than once that the real enemy in this apocalypse isn’t the walkers, but other humans.

Also, while the Kingdom still feels fairly relaxed, both the Hilltop and Alexandria seem extremely wary of outsiders. Alexandria attempts to keep itself well-hidden, to the point of keeping outsiders blindfolded on the way to their destination, and the Hilltop farmers have an alert system that sends their members running inside their walls if riders approach. While we can’t speak specifically to what happened between the communities, it feels likely that an outside influence scared everyone into some kind of hiding. It also feels likely that the confrontation was extremely traumatic.

WHAT ARE THE Xes?

Michonne and Daryl both have X-shaped scars, or brands, on their backs, and they’re probably the two characters who’ve been the most resistant to welcome newcomers (in Michonne’s case) and leave solitude (in Daryl’s case). We feel safe saying the marks aren’t there to signify who missed Rick the most. They were clearly put there as a result of some sort of confrontation, although we can’t begin to know what that was. Given Michonne’s rhetoric and wariness of outsiders, it seems likely that an invasive force (perhaps the same one that resulted in the breakdown of community relations) is responsible. Or is it?

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While the communities keeping to themselves and Michonne’s mistrust of Magna and her group would seem to indicate an outside force had tried to upset things at some point, it’s also possible that no outside force was necessary to obstruct relations between the communities. There were already significant disagreements in ethics and policy before the time jump, as evidenced in the deep philosophical split between Rick, Maggie, Michonne and Daryl. Cassie executed vigilante justice freely and with the tacit approval of Maggie and Daryl, and that’s something Michonne would have been furious to learn about.

Also, Rick’s death and Michonne’s pregnancy would’ve inspired everyone’s favorite post-apocalyptic samurai to dig in her heels about any issue that affected the safety of her family. Considering the communities were in a delicate stage of nation building before the loss of Rick’s leadership, it’s very possible that some kind of civil war or dispute is responsible for the breakdown in relations and even for the abuse Michonne and Daryl suffered. And that would be kind of fitting considering it’s the communities fractured relationships that have left them so vulnerable to attack from this mysterious new enemy.

WHO ARE THE NEW WALKERS?

While in transit from the barn to safety, Eugene gave a plausible explanation for the strange new behavior of the walkers that seem to be stalking him. Instead of becoming distracted by other noises like normal walkers would, this herd seemed to follow him, and later the Jesus, Aaron and Daryl. They weren’t turned away by the firecrackers or timers Daryl threw in their path, and they seemed to remember where Eugene was hiding and came back to find him. Also, as Eugene, Rosita and the audience could hear, they actually seemed to be whispering to each other.

Putting a pin in just how terrifying that was, Eugene reasoned that communication and stalking were evidence of evolution among the walkers. While the others scoffed at the notion, Eugene pointed out that it wasn’t any stranger than the walkers’ existence in the first place. He also pointed out that their colloquial classification as “undead” wasn’t technically accurate as they were actually alive, just with a minimal amount of brain activity. He reasons that if there’s brain activity, there’s room for the brain to evolve, hence the new behavior.

That seemed plausible (if horrifying) until Daryl discovered otherwise in the graveyard after Jesus’ death. The walkers had not evolved; humans had simply been posing as walkers and wearing their skin, creating some sort of hybrid predator unlike anything the survivors had ever seen. What we can expect from these new antagonists remains to be seen (unless you’re a comics reader, in which case you have a very significant idea of what to expect. Hint: It’s not good.).

Airing Sundays at 9 p.m. ET/PT on AMC, The Walking Dead stars Norman Reedus, Danai Gurira, Melissa McBride, Alanna Masterson, Josh McDermitt, Christian Serratos, Jeffrey Dean Morgan, Nadia Hilker, Dan Fogler, Angel Theory, Lauren Ridloff and Eleanor Matsuura.