The Defenders wastes little time introducing Marvel fans to Alexandra, the Big Bad played by Sigourney Weaver. Spoilers for The Defenders premiere ahead. As a leader of The Hand, she even seems to intimidate Madame Gao. What's her deal, exactly? Is she immortal? She sure seems to act like it. If that is the case, it seems even more possible that The Defenders' villain Alexandra is from K'un-Lun. The Netflix antagonist could be connected to the New York City heroes in a few ways.
The ancient, mystical city that took in Danny Rand after his parents perished in a plane crash was seemingly destroyed by The Hand at the end of Iron Fist Season 1. That said, the metaphorical jury is still out on whether or not The Hand is a united group, or warring factions who have experienced a schism. Bakuto's group may have been working independently in Iron Fist. Perhaps the destruction of K'un-Lun is what is calling Alexandra to action in The Defenders.
Alexandra is introduced in the first episode as a wealthy woman suffering from a terminal disease. She's dying — plain and simple. That said, as easily as feeding the birds in Central Park, she starts dropping hints to the audience that she may have lived for centuries. "It must be hard for these people to imagine the whole island of Manhattan as a forest," she muses.
Madame Gao has communicated her intent to return home before, wherever that may be. It's heavily implied in Daredevil that she means K'un-Lun and may even be the Crane Mother herself. If Gao's home is indeed the lost city, it's possible that Alexandra has a similar origin. Maybe the Crane Mother is Alexandra, or was once upon a time.
It's definitely something to watch out for on The Defenders. As far as Marvel fans know, Alexandra is an original character not from the comics. So anything can happen, really. As of the first episode, she seems to be a big history buff with an interest in New York City's origin story. While that doesn't sound like someone who lived in a hidden city that keeps its gates locked for fifteen years at a time, one does wonder how she got to be where she is today. K'un-Lun, which the Hand seems to be fascinated with to the point of obsession, may hold the key.