Some Serpentine headcanons:
When a Hypnobrai hypnotizes someone, they see a basic glimpse into their mind, but this glimpse becomes more detailed the longer they have the hypnotized subject under their control. While for most this glimpse disappears once they stop hypnotizing their target, others may unknowingly form a unique bond with their victim, being able to read them mentally. This can persist even after those hypnotized are treated with antivenom.
Some Pyro Vipers suffer from pyromania. As such, they are kept under close watch so that they don't start any fires. The revived Pryo Vipers can eat and drink just like any other living thing, but they have to be careful not to burn what they're eating. (There's also the fact that it's possible that some of the previous Pyro Viper kings were revived along with there subjects, it's just that they're keeping a low profile.)
Some Fangpyre have a some type of mutation where they produce less venom, but said venom can't be cured by getting the victim's heart rate high enough, meaning that their only solace is the Fangpyre antivenom. Some Fangpyre also have a strange thirst for blood (both human and Serpentine), but they can also eat and drink normally (though they like the blood more).
There are a few Venomari who are born with six eyes instead of four, with the extra pair of eyes functioning normally. There's also some Venomari whom have either more acidic yet less hallucinogenic venom, or more hallucinogenic yet less acidic venom; those whom are afflicted with the more acidic venom may get acid burns, while those suffering from the more hallucinogenic venom may see hallucinations months after they get cured.
Some Anacondrai are born with legs instead of the usual tail. These individuals, while ostracized from Anacondrian society, learn that having legs may not be a necessarily bad thing, and that they might be able to do things that regular Anacondrai can't (ex. wall climbing). There are also some Anacondrai whom are born with a unusually long neck (like Pythor), which not only makes them stand out from their brethren, but also makes them more susceptible/prone to suffer vertigo.
Some Constricti are born with an extra pair of arms, and are slightly taller as a result. Those with this condition are more efficient at digging, as well as being a formidable foe in combat. There are also those whom suffer from Pica, which causes them to eat things such as rocks, dirt, sand, etc; these individuals have to be closely monitored, as they can eat something (ex. glass) that could cause sometimes fatal internal injuries.
Above all else, there is a small chance that any Serpentine can be albino, leucsitic, piebald; abundistic, or melanistic. Also, Serpentine can live up to 200 years, and grow up somewhat faster than humans.