The only thing we know for sure about Kai and Winter Anderson, is that the pair of them are creepy as hell. Kai's intense, alt-right, fear-mongering attitude and assertion that there's nothing scarier than a humiliated man would send chills down the spine of any left-wing liberal. Winter, who dresses as if she would be perfectly at home in New Orleans with the ladies of American Horror Story: Coven, shows murder videos to young children. But is their shared creepiness a familial trait?
Are Kai and Winter related? Or are they married? Could they be members of the same cult? Are they just roommates? How does Kai even know Winter on American Horror Story: Cult? There are a million fan theories and episodic evidence to help puzzle out what's up with Kai and Winter.
They're the Andersons! But what does that mean? Just what are they to each other? Brother and sister? Husband and wife? Two people with no relation who happen to share a fairly common last name? Maybe "Anderson" is a last name given to all members of the cult they're in? They could be like the Manson family, but if you swapped Manson for Anderson. Are they cousins? Step-siblings? Are they even related by blood at all?
Their shared last name certainly suggests a close bond, whatever it is.
Many people seem to think Kai and Winter are siblings not only because they share a surname, but because they share more than a passing resemblance and seem to live in the same house. Not to mention, their pinky finger ritual smacks of a childhood sibling game and none of their interactions have read as overtly romantic thus far.
And one eagle-eyed Redditor, lav4567, spied a stair-lift in their shared house. It would appear Kai and Winter are living with an older roommate, as both Kai and Winter are able-bodied and stair-lifts are a household item associated with older folks. Could the stair-lift belong to their shared mother or grandmother?
A disabled family member might explain why they have so much freedom to go about their crazy business.
Of course, people can share a last name and not be related by blood. Perhaps Kai and Winter are actually husband and wife? A husband and wife that appear to sleep in separate rooms and have completely oppositional political views, that is. Though, if they are married it may not have been a love match; these two might have had to get married in some kind of creepy cult ritual. The ins and outs of the cult haven't been revealed to the audience just yet, so maybe weird marriages are a membership requirement?
One aptly named Redditor snowflakefairy, realized that Kai and Winter Anderson may be named as a reference to Hans Christian Andersen and his fairy tale The Snow Queen. The protagonist of the story is a boy named Kai who gets shards of a mirror that only reflects the evil side of the world, in his eye. The Kai of American Horror Story seems to only see the worst, most fear-inducing aspects of the world.
Fairy tale Kai gets kidnapped by the Snow Queen during the winter. Not only is Winter's name seasonally appropriate, but maybe she's meant to represent the Snow Queen in the show? And if that's the case, maybe Winter is the cult's head honcho and she recruited Kai?