Character development is almost always a death sentence for second-tier characters on The Walking Dead. When a previously peripheral character suddenly gets a meaty storyline or an interior life, it usually means they're about to die. The show has always operated like this. But when done well, it's still effective. Siddiq's (Avi Nash) final moments in "Open Your Eyes," the seventh episode of Season 10, were sad and shocking, even if we've seen scenes like this many times on The Walking Dead.

Siddiq was introduced at the beginning of Season 8 as part of Carl's (Chandler Riggs) death storyline. Carl got bit while saving Siddiq, and after Siddiq vowed to keep Carl's memory alive and ensure that he didn't die in vain, he receded to the margins in the second half of Season 8 and most of Season 9 as he worked as Alexandria's doctor. Then, at the end of Season 9, Alpha (Samantha Morton) forced him to bear witness to the massacre of his friends, which made him an important character once again.

Throughout the first half of Season 10, Siddiq struggled with PTSD due to what he saw. He tried to be a good doctor to his community and a good father to Coco, his daughter with his ex Rosita (Christian Serratos), but he was experiencing flashbacks and panic attacks and sleepwalking episodes that were making it difficult to function. It came to a head in "Open Your Eyes," the series' first Siddiq-centric episode, which is also going to be its only Siddiq-centric episode.

The Walking Dead May Have Just Started the Beginning of the End

He and his medical assistant Dante (Juan Javier Cardenas) went to evaluate the Whisperer prisoner Carol (Melissa McBride) brought to Alexandria. "I know you," the prisoner said. "Looook." This triggered another flashback in Siddiq, since "look" was one of the things the Whisperers said to him while they were forcing him to watch them kill his friends, along with "open your eyes." Dante sent him out of the jail cell and he took care of the prisoner himself.

Siddiq went to visit Rosita in the infirmary. She, along with many other Alexandrians, were sick with some kind of stomach bug that Siddiq was unable to find the cause of. They cuddled, and he said that he just wanted to do right and be a good dad to Coco. "She's lucky to have you," Rosita said. "We both are." He almost kissed her, but then she had a coughing fit and the moment was ruined. The scene was a glimpse of hope that maybe two people who should be together would be, but hope is a dangerous thing on The Walking Dead.

Later, the prisoner got very sick and died because Dante gave him poisonous hemlock instead of healing yarrow, which Dante blamed on Siddiq making a stress-induced mistake. That, combined with the death of Sheryl, an elderly Alexandrian Siddiq was caring for, induced a panic attack so severe that Siddiq jumped in the stream to cool himself down and maybe drown. Rosita pulled him out and tried to get him to talk about what was going on with him, and he finally opened up about his PTSD.

"It's like I'm still there all the time," he said. "It's like I never left." He said he missed his former assistant Enid (Katelyn Nacon), and every time he looked at Dante he thought of her. He blamed himself for not doing anything to stop the massacre. Rosita said he had to pull through, for Coco and for everyone, and he would be able to because he wouldn't be alone. And since they were sitting by the water while they were having this conversation, he realized that the common denominator that was making everyone sick was the drinking water — which Dante had surreptitiously marked as "drinkable" when he knew it wasn't and had been distributing in Eugene's absence. Siddiq didn't know that the source of the poison was the walker bodies that Gamma (Thora Birch) was dumping in the stream, which he died before he could figure it out, but someone will have to.

Avi Nash, <em>The Walking Dead</em>Avi Nash, The Walking Dead

And then, the final moments. Dante came to talk to Siddiq, and reiterated that Siddiq is not alone and everyone is in it together. Then he made a little mouth-click sound, and Siddiq realized that Dante was the Whisperer who held his eyes open and made him watch. He tried to fight him, but Dante put him in a headlock and choked him to death. "I didn't want this. Not you. Not like this," Dante murmured. "Close your eyes." But he didn't. Siddiq died with his eyes open.

The twist came as a surprise, but looking back, there was at least one hint about Dante. In the season premiere, Siddiq zoned out staring at Dante's mouth, which would have been the only part of Dante's face under the mask that he would have been able to see clearly. It'll be interesting to see what Dante's ultimate goal in Alexandria is. He's trying to poison people and sow discord, but is there something specific he's working to accomplish? It seems like he's working very deep undercover, as Alpha (Samantha Morton) and Beta (Ryan Hurst) would haven't even alluded to having someone on the inside during their strategy sessions. It's also strange that neither Lydia (Cassady McClincy) nor the prisoner seemed to recognize him. It'll be interesting to see how he gets out of this. Probably he will stage it to look like a suicide. And since Dante will be the medical examiner, no one will check Siddiq's hyoid bone.

Avi Nash's performance in this episode was very strong, and it will be cool to see where his career goes from here. He was basically unknown when he joined the show two years ago, and now he's a guy who was on The Walking Dead. The show has launched a lot of careers. Tom Payne, the Siddiq of last season, is now the lead on a fairly successful broadcast show. Cry for Siddiq, but don't cry for Avi. He's just getting started.

The Walking Dead airs Sundays at 9/8c on AMC.