I've come to realize that my "new" cat (Nyx, not so Siamese, F 2yo) is extremely serious. She hates when Circe (Tuxedo, F 2yo) gets zoomies and starts stalking her. When Circe starts running and jumping around, Nyx gets up from whatever she's doing to follow her around, but when Circe takes it as they should play together, Nyx will either meow in distress or hiss.

Tiring Circe out doesn't work much bc Nyx does play when I'm in control, but she still gets fed up when Circe gets too close as they play. I've also tried distracting Nyx when Circe gets her zoomies, but Nyx is too down bad to stalk.

I'm wondering if there's anything I can do to make Circe calm down or Nyx take a chill pill.

Other than this, they are good together. No cuddles between them, and I can tell that they have tension bc they no longer both sleep on the bed with me, but I think they just need time.

Quick recap of introducing them:

Got Nyx in January, took 2 weeks to introduce them, and they had a big fight. 

Then I separated them for a month and slowlier introduced them over 2 months.

They are both spayed and have access to a vet.

They are now comfortable living with each other and they are separated only when things get a little tense (a few hisses withing a couple minutes) around once or twice a week.

TLDR: Nyx is too serious to play with Circe but can't let her play without stalking her. Nothing has helped and I'm getting fed up with Nyx playing the victim card.

Why won't they just love each other!?