Dr. Singh's Shocking Turn Against Gus in Season 3 of 'Sweet Tooth' Explained

Spoiler alert: This article contains spoilers for Season 3 of Sweet Tooth.

When Dr. Aditya Singh (Adeel Akhtar) first makes contact with Gus (Christian Convery) in Season 2 of Sweet Tooth, he can’t fathom the idea of putting him under the knife. After all, he is the first hybrid he meets that can speak, let alone behave like a human being. But in Season 3, we see an entirely different side of Dr. Singh, and I’m not quite sure if I like it.

In the third and final season of the Netflix series, Dr. Singh, once known for his sympathetic side and occasional vulnerability, becomes cold and somewhat heartless. He even believes it is his destiny to kill Gus, a hybrid he once cared about and protected. But why?

Dr. Singh doesn't want to kill Gus out of personal dislike or a desire to eliminate hybrids like most humans. Instead, he believes sacrificing Gus is necessary to save humankind, aka cure The Sick. The doctor, likely the last one on the planet, arrives at this notion after a dream in which he sees himself entering a cave holding a lifeless Gus. In the dream, he also holds a bloody knife, which he believes he must use to carry out the act once inside.

What further convinces Dr. Singh that he must offer up Gus is the fact that he and Gus both had visions inside or near this mysterious cave which we come to learn is where The Sick and the hybrids derived from in the early 1900s. While the virus had “died” with Dr. James Thacker, his crew, and a native woman named Ikiaq, the samples Fort Smith took when they returned to the cave decades later brought it back to life.

One key difference between Gus and Dr. Singh’s dream, however, is that Gus envisions himself in the freezing cold cave looking for Birdie. Dr. Singh, on the other hand, also hears an echoing of Thacker’s voice saying “All was unlocked when I sacrificed the deer" shortly after reading those same words on a page in his journal.

Therefore, he believes it is Gus’s blood that will undo what Thacker did, and ultimately cure The Sick, thereby allowing the world to restore itself back to the way things were before the virus began wiping everything away.

It’s safe to say that Dr. Singh's shift from not wanting to harm Gus to wanting to end his life marks a significant change in his character. However, we've seen him repeatedly set aside everything, including his morals, in his quest for a cure.

After losing his wife Rani (Aliza Vellani), the one thing keeping him going, Dr. Singh now believes that sacrificing Gus and curing The Sick will fulfill his purpose. He hopes this act will be enough to wipe his slate clean and allow him to reunite with Rani.

While he may have been wrong about the need to sacrifice Gus, Dr. Singh was right in believing that Gus is "the key to fixing everything," as he explains to Zhang (Rosalind Chao).

In Episode 10, Gus slices his hand with the same knife Dr. Singh saw in his vision and presses it against the cut in the tree, mixing his blood with the blood of the Earth. Just moments before Jepp (Nonso Anozie), Becky (Stefania LaVie Owen), and the others in the cave take their last breath, Gus then burns down the mystical tree, and they live.

Despite him running around with a target on his back for nearly the entire Sweet Tooth series, Gus doesn't die. In his attempt to cure The Sick by placing his bloody hand against the mystical tree, he's transported to a realm, perhaps what some might consider to be the place between life and death, and encounters his Pubba.

After they begin speaking, Gus comes to a profound realization that the fires his Pubba would often speak of symbolize The Sick. He then understands that nature set the world "on fire" to punish humans. However, his Pubba imparts a deeper wisdom, explaining that death is a natural part of life and that nature is ready to move on.

In an attempt to bring Gus back conscious, Big Man, who is barely holding on at this point, calls for him to return, and then appears in the mysterious, yet peaceful realm. Gus awakens and sets the tree ablaze, which ironically bears branches that closely resemble that of deer antlers. Those around him who contracted The Sick are immediately cured, and Gus and his "family" are able to return to Yellowstone.

By the end of the series, we see a much older Gus (played by James Brolin) telling his story to a group of young hybrids. It's hinted that Big Man and any other surviving humans have long passed, leaving Gus to keep their legacy through his stories.

While Dr. Singh had no luck finding a cure for The Sick in Season 2, his determination remained intact, and he was hellbent on keeping his wife, Rani, alive. Unfortunately, Rani grew tired of watching her husband’s relentless efforts to find a cure and decided she could no longer stick around to witness more failed attempts. Without even a goodbye, Rani leaves Dr. Singh at the zoo and presumably dies without any more "secret sauce" to keep her healthy.