Sweet Tooth is the new Netflix fantasy series based on the Jeff Lemire comic books from Vertigo. The series takes place a decade after a disease wiped out much of the population, while at the same time several women gave birth to animal/human hybrids. The public acted in a reactionary manner, blaming the hybrids for the disease and setting out to kill these children.
Along with the same people who are killing kids for a disease that ravaged the world, there are also very smart people, working to find a cure. Sadly, many of these scientists are conducting unethical research that once again puts these children, including Sweet Tooth's central character Gus, in grave danger.
Gus
The main character in Sweet Tooth is Gus, a deer/human hybrid. He is arguably the most intelligent hybrid character on the show, as he is the only one who can talk and was raised like a human boy, getting an education and learning how to read. However, his dad raised him in a cabin in the secluded woods and he never met anyone outside of the cabin until right before his dad died. Gus has a lot to learn, and he does in the comics, but in the Netflix series, he is still discovering the new world.
Pubba
Gus's dad is Pubba, and he took the child to the remote cabin in the woods and raised him there in safety. Pubba taught Gus how to talk and instructed him in the basics to stay alive, including running and hiding from humans for his own safety. However, Pubba never prepared Gus for living outside this cabin, and with danger around every corner, he did the boy no favors keeping him so insulated from the truth. However, while Gus was created in a lab, Pubba was a janitor. While he wasn't a scientist, he was still resourceful.
Rani Singh
Rani Singh exists mostly to give viewers a reason to like Dr. Singh in the Netflix version of Sweet Tooth. In the comics, Dr. Singh first appeared in a lab, experimenting on hybrid children's corpses, trying to find a cure. He seemed insufferable with a godlike complex. In the streaming series, Dr. Singh appeared much earlier and had a wife who had the sickness. She was there to help encourage Dr. Singh in his studies and shared his horrors at the experiments he could be forced to conduct. She seemed smart, but had little to do in the first season.
Tommy Jepperd
Tommy Jepperd is a former football star; he was a hockey player in the comics. He isn't the brightest person in the world when it comes to brain smarts, but he is very resourceful. Jepperd is smart enough to know how to stay alive and he is strong enough to fight his way out of trouble when needed.
Early on, Tommy told a couple that he did what was needed to help others survive and now he is beholden to help Gus survive and get to safety. He also has a lot to fight for, as his wife and son might still be alive, after disappearing early in the sickness.
Aimee Eden
Aimee Eden is a brand-new character for the Sweet Tooth Netflix series, someone who never existed in the comics. She was a therapist who seemed to loathe her life listening to married couples discuss their marriage problems. When the sickness started, Aimee locked herself away in her office and stayed there while everyone else ran and died. She eventually came out and created the sanctuary at the zoo, where she tried to help hybrid children. As a former therapist, she is clearly more intelligent that others in the series.
Bear
Much like Tommy, Bear is another character who might not be the most intelligent person in Sweet Tooth based on IQ, but she is someone who is very smart and resourceful. She survived in much the same way as Tommy, knowing what to avoid when the bad guys showed up. She is also resourceful, taking it upon herself to lead her pack when it comes to going out to rescue the hybrids and help them survive this post-apocalyptic future.
General Abbot
General Abbot is the antagonist in Sweet Tooth. In the comics, he was the man who led the Preserve, which was the scientific institute that abducted and experimented on the hybrid children to try to find a cure for the disease that decimated the planet.
In the Netflix series, Abbot (played by The Flash's Neil Sandilands) leads the Last Men, the surviving humans who hunt down and either kill or abduct the hybrid children to take in for experimentation. He is also who eventually brings in Dr. Singh and forces him to begin to experiment on the children against his better judgment.
Dr. Aditya Singh
Dr. Aditya Singh was a medical doctor when the sickness struck. He was also one of the first doctors to go into the hospital nursery and see all the hybrid children. Singh chose not to practice medicine anymore and stayed at home, helping his wife stay alive while hiding her condition from neighbors who would kill her if they found out. He eventually took over as the lead scientist trying to find a cure to save his wife's life, and he is the best hope for the survival of humans.
Dr. Bell
Dr. Bell worked many years trying to find a cure to the sickness. While she never found the cure, she had notebooks full of notes on her experiments on the hybrid children. She also found temporary antidotes to help keep Dr. Singh's wife alive, so she did more than most doctors accomplished in the world of Sweet Tooth. When she developed cancer, she was smart enough to pass on the information to Dr. Singh, knowing that his wife was enough to make him the perfect person to carry on her work.
Birdie
Birdie wasn't a big part of Sweet Tooth's first season. However, in the seventh episode, "When Pubba Met Birdie," the show reveals she might be the most important. Sadly, the smartest people are often the most dangerous, and that is the problem with Birdie. It was Birdie that helped caused the H5G9 virus that wiped out much of the world while also creating Gus. It is Birdie who helps rescue Gus from the lab and sends him off with Pubba for safety, while she went on the run. In the finale, Birdie turned out to still be alive, and she might be the key to finding a cure.