WARNING: The following article includes spoilers for The Walking Dead Season 10 premiere, "Lines We Cross," which aired Sunday on AMC.

Following the death of Andrew Lincoln's Rick Grimes, fans have been speculating about who would be his successor on AMC's The Walking Dead. Michonne was one name thrown into the hat but with Danai Gurira exiting soon, that can be ruled out. Meanwhile characters such as Daryl, Ezekiel and Carol aren't being lined up to take Rick's mantle as leader of the alliance.

However, as Season 10 opens with the episode "Lines We Cross," we see Ross Marquand's Aaron picking up right where Rick left off as co-leader of Alexandria. Sadly, though, his behavior is already problematic and could spell doom for everyone working together to fight off the Whisperers.

RELATED: The Walking Dead Season 10 Premiere Sets Up an Inevitable Clash

In this premiere, we see that the apocalypse has been weighing on Aaron, and now he's breaking. He was a recruiter for Alexandria, and along with his boyfriend, Eric, brought Rick and his people in, thus giving birth to the alliance we know today. Aaron quickly became one of Rick's most trusted allies. However, when Eric was killed by the Saviors in Season 8, Aaron quickly became depressed. He grew through his grief, learning from Jesus more about being on the front lines. Yet, it seems he's past the grief stage and into anger now, especially after the Whisperers placed his friends' heads on spikes and declared an uneasy border.

Aaron's now working with Daryl and Michonne to train their soldiers at Oceanside. Yet, they're all taken aback when a Whisperer mask washes up on the beach. Aaron goes off the edge, immediately thinking Alpha and co. are going to be returning for battle. So in response, he haphazardly starts killing Walkers out on the streets. Michonne tries to calm him down. She doesn't need him unnecessarily running off with his one arm into danger.  She also doesn't agree with his desire to place Alexandria and Hilltop on red alert via radio. Michonne urges him to play it cool and let them explore and assess, but Aaron wants to start battening down the hatches and dispatching teams for war.

He argues with Michonne -- much like Rick did when their philosophies differed -- and makes it clear after the deaths of people like Rick, Jesus and Eric, they can't play it safe. They need to stop being defensive and go on the offense, which he thinks would have saved Rick. Poetically, the pair hash it out on a bridge. Michonne is reminded of Rick's death as she warns Aaron that his erratic behavior will be their undoing, not to mention it'll spread fear and panic.

RELATED: The Walking Dead: How Michonne, Ezekiel Romance Influences Season 10

He eventually calms down but you can tell there's tension. And with this creeping dissent, Aaron's not likely to be following orders to a tee. He's also questioning if they're really the good guys in this story, which hints at a future civil war where Aaron may desperately recruit people to his side.

His relationship with Michonne actually mirrors Rick and Dwight's relationship from the comics, and that ended badly at the Commonwealth with Rick having to kill Dwight to maintain peace there. It probably won't go that far in the show, but Aaron's clearly not composed enough to be in a leadership role. He's been a diplomat and politician in the past, but he's way too emotional and invested to be making key decisions right now.

With Lauren Cohan's Maggie returning as a series regular, Aaron could find himself taking a backseat. Or who knows, maybe his actions will cost him his life. The way he's behaving, the latter's very possible. Fans are hoping if Aaron goes down, he doesn't take anyone with him because of his impulsive mindset and overall irresponsibility. He may talk and act like Rick. He may look like him with the beard. Heck, he even has one hand like Rick in the books. However, right now, Aaron is a far cry from the man who guided the group of survivors this far in the zombie apocalypse.

The Walking Dead stars Norman Reedus, Danai Gurira, Melissa McBride, Josh McDermitt, Christian Serratos, Jeffrey Dean Morgan,Seth Gilliam, Ross Marquand, Khary Payton, Cooper Andrews, Avi Nash, Samantha Morton. It airs Sundays at 9 p.m. ET/PT on AMC.

NEXT: The Walking Dead: Where Each Character Is in the Season 10 Premiere