The Ananta clan is known for their specialty in poison and their deceptive nature, at least according to the Garuda clan.
During the time when Ananta, the first King of the clan, was alive, the Ananta clan claimed the title of the strongest clan among the suras. However, because they relied heavily on Ananta's power and he was considered invincible, the clan was caught in a dire situation at his death as their predators grew stronger.
After Ananta's death, Vasuki, the second strongest nastika within the clan, took female form to avoid succession. Subsequently, the position of the King was taken up by the next qualified candidate, Manasvin. Shortly after the N0 Cataclysm, Manasvin disappeared after a few negotiations with the Gandharva clan regarding a plan of his.
Through questionable means, Sagara took up the position instead of the strongest nastika in line, and the relationship and loyalty between her and other nastikas from the Ananta clan has been strained ever since. This is important because Sagara is considered weak for a nastika and having her as King makes the whole clan look weak in the eyes of others.
Currently, Sagara is in the human realm thanks to Kubera's portal along with her army, trying to find and kill humans which hold the name of Kubera. With Maruna's assistance, they destroy many smaller villages where name holders reside before they target their first large city, Atera. They attack the city twice but fail both times, the second because of Agni's return. Later, Sagara and her army attack Kalibloom in order to obtain Kubera's god-class items during the Test of the Sword. Sagara infiltrates and attacks Leez during her test, where she overpowers and nearly kills her. Sagara and her army have set their sights on Rindhallow next.
The Ananta clan is distinguished by their serpentine feature in their sura forms. While they do not necessarily take form of snakes (for example, Cloche has wings and Clophe has arms, which snakes normally do not have), their form is defined with long and thin bodies, attached to relatively small and triangular heads and possessing a split tongue. This clan is also notorious in their proficiency in the use of poison and deception.
Probably due to their strength in the past, the Ananta clan has accumulated more notable population than other sura clans, resulting in a rather threatening military power for humans. They are natural prey for the Garuda clan, though the situation was not as desperate when Ananta was alive. Now, as the Garuda clan and the Ananta clan have similar power, it seems they are hunted down more than in the past. For example, Maruna is known for preferring Ananta clan prey than other sura creatures. Pingara has been a constant target for Maruna due to his/her large physique.
The Ananta clan is allied with the Asura clan, probably as a countermeasure to the Garuda-Gandharva-Yaksha alliance. As mentioned above, due to their prey-predator relationship, the Ananta clan is hostile towards the Garuda clan. With a weak king like Sagara on the throne and the internal division within the snake clan, the Garudas should have easily annihilated their enemies, but since their own king is in a coma they are no longer as strong as they used to be. Still it would seem the Anantas are in a precarious situation, as Maruna alone has been mentioned to be able to deal massive damage to Sagara's forces.
As mentioned above, nastikas from the Ananta clan pledge no loyalty to the current king, Sagara. Sagara's army consists of some rakshasas, some of them speculated to be Sagara's own offspring, and lower rank suras. As of this point, the only Ananta nastika that does not have any murderous intention towards Sagara is Vasuki. Actually, it is thanks to Vasuki that Sagara is able to maintain her status as King. Due to Vasuki's support for Sagara, other nastikas are afraid to kill Sagara for their own benefits as it will mean immediate retribution from Vasuki, thus maintaining a frosty and silent atmosphere within the clan.