An encounter with Alpha (Samantha Morton) and the Whisperers has left Siddiq (Avi Nash) mentally scarred and "losing his mind."
In the months since the Whisperers abducted him and forced him to witness the gruesome murders of protégé Enid (Katelyn Nacon) and nine other friends, including interim Hilltop leader Tara (Alanna Masterson), Siddiq is suffering from the lingering effects of an act of terror that has left him with PTSD.
"Torturous is a great word. I think he saw some of the worst things that anyone can imagine," Nash told EW at Comic-Con, where the premiere of the first Season 10 trailer showed a shaky Siddiq experience a panic attack.
"He saw Alpha's cruelty first hand, and he lived to tell the tale, and he's got PTSD now, as one would, and survivor's guilt. He's just trying to extract himself from that nightmare, and it doesn't stop. That's the scary thing of having PTSD, you don't know when you're in your memory and when you're in reality. He's losing his mind."
That turning point from the penultimate episode of Season 9 — where Michonne (Danai Gurira), Daryl (Norman Reedus), Carol (Melissa McBride) and Yumiko (Eleanor Matsuura) were horrified to stumble upon the decapitated heads of ten victims, including Carol's son Henry (Matt Lintz) — is burned into the survivors' minds.
Like Carol, who suffers from horrific visions of Henry's bloodied corpse, the survivors are haunted by the devastating aftermath of the fair.
"We're dealing with a lot of things also to do with people's trauma, and the idea of what is real or not real. Things having to do with illusion, or just memory breaking, PTSD," showrunner Angela Kang told EW.
"So there's a lot of stuff that we're doing that's pretty unique to the feel of this season."
The Walking Dead premieres its Season 10 opener Sunday, October 6 on AMC.