Not specifically Charlie, mind you, it's just that the only person that Gladiia has invited to Rhodes beyond Charlie is Nata, who Gladiia has come to trust. There's a lot about Charlie, meanwhile, that Gladiia just doesn't entirely trust. They're a little too friendly. A little too good with a blade. A little too willing to show up with gifts at her doorstep. Nothing that'd make Gladiia make them into a missed connection, but enough to give her pause about the concept of leaving them unsupervised around people she cares about. She's a paranoid person, and she didn't even completely trust Nata at first, until a lapse of judgment during a moment of profound weakness and sleep deprivation put her into a situation where she was forced to trust her. She has no idea that Charlie is a serial killer, but if she learned that, her own paranoia would convince her that she saw it from the beginning—and she did, technically, she'd just also see predators where normal people stand nine times out of ten.
Beyond the minor distrust, though, Gladiia thinks well of Charlie. They're a good dance partner, and she appreciates someone who's proud of their work and has gotten quite good at what they like. She would not mind at all their sparring sessions and movie nights becoming a regular occurrence. */