Although there was supernatural business going on, Riddled didn't feel like a Teen Wolf episode, but a dark and excellent extended metaphor for mental illness. Anchored by show-best performances by Dylan O'Brien, Tyler Posey and Holland Roden, Riddled is Teen Wolf's finest hour to date, and one can't help but wonder how they can possibly top it.
Stiles is sick, really sick. Remember how last week, it was revealed that Stiles shares the same symptoms as his dead mother? Well, the condition is called frontotemporal dementia, in which areas of the brain begin to shrink. The condition has no cure, killed Claudia Stilinski, and is the only form of dementia to affect teenagers. It is also potentially this condition that allowed the nogitsune to possess him. This, like the Buffy episode The Body, is the truly terrifying thing: a wholly un-supernatural menace that cannot be stopped. It is all revealed in a beautifully heartbreak scene where, awaiting Stiles' MRI, Scott assures him that he'll do something (implying he'd offer Stiles the bite if diagnosed) while the Sheriff and Melissa look on, close to tears. Clearly building on their real life friendship, O'Brien and Tyler Posey are wonderful here, and every second of the scene feels raw.
While all this is happening, Derek accompanies Kira to where Barrow held her hostage, finding Stiles' magnetized bat inside. Together, they discover that Barrow used Kira's foxfire to kick-start Stiles' possession. Kira is clearly more deeply involved than we're currently aware, and events later in the episode indicate just how much. These few, brief scenes see Arden Cho and Tyler Hoechlin interacting nicely with each other, and hopefully Derek and Kira can share more scenes in the future. Meanwhile, Lydia is almost deafened by the changing of Stiles' MRI, and it looks like she will be crucial to future plot developments.
The battle in Stiles' head continues during the MRI, with the confrontation between him and the bandaged man taking on an extra nightmarish quality when the man is revealed to be Stiles himself, but a noticeably darker Stiles. This is the nogitsune, and its taking over. The power shorts in the hospital, and the possessed Stiles escapes the MRI room, only to be confronted by Mrs Yukimura and the Oni. It was hinted earlier in the episode that Kira wasn't the only kitsune in her family, but her mother controlling the Oni is a genuine surprise. Stiles as the nogitsune is deliciously creepy, and it is implied to powerful to be defeated by the Oni, but Mrs Yukimura says someone else can stop it. Cut to Kira.
One final curiosity. Since she stopped hallucinating the presence of Kate Argent, Allison has been fairly absent from the narrative. This week, she sleeps through the entire hunt for Stiles, and when Isaac finally catches up with her, her phone is filled with voicemail messages in Japanese about an internment camp. What this all means, we don't know, but could Allison be more involved than we have been led to believe?
The biggest weakness of Teen Wolf has always been plot inconsistencies, but with this season, the writing is coherent and building a strong narrative. Only time will tell if some omissions (such as Allison's hallucinations) have been done so intentionally, but with a run of three incredible episodes, it would be a shame to not see that streak continue. On top off this, the characters seem to have fully found their purpose, especially tonight with Derek taking on the role of mentor. His teaching Scott to be a better alpha than he could have ever been, and the letting go of a lot of his anger, shows a great deal of character development, and subtly done. The show has said it's moving away from action to explore psychological horror, and it's all the better for that change.