CatOne = 2-yr-old spayed female, lives indoors, claws intact, sweet girl
NewCat = 1-yr-old neutered male, claws intact, affectionate but rowdy

NewCat joined our household three weeks ago today. We introduced the two
slowly (7 - 10 days before opening a door between them), as all the books
say to. Every time we allow them to be without a door between, CatOne
hisses, runs, and hides. NewCat chases her, we think in play, but when he
catches up to her there's lots of hissing, snarling, growling. That always
happens under a bed or sofa so we can't tell who's doing it but we think
CatOne. Then CatOne takes off again. We separate them when it starts to
sound really ugly. Oddly, within 15 minutes or so of separating them,
CatOne is back to happily being herself. No sulking.

We've tried:
Treats when they are calm with each other (happened only once, erupted into
a yowling chase),
Separate carriers next to each other,
NewCat in a carrier but CatOne not,
Feliway spray,
Bach's flower Rescue Remedy.

I spoke to an animal behaviorist, recommended by our vet. She said that it
sounds like CatOne is a quiet demure girl (she is) and NewCat's
rambunctious, teen-age boy energy is too much for her. She was surprised
that CatOne has not urinated inappropriately to show her displeasure. When
I told her we were considering finding a new home for NewCat, she said that
would be one appropriate course of action.

We are heartbroken, but feel it's unfair to CatOne to continue to force
this NewCat on her, and we don't want CatOne to be miserable. When we
adopted NewCat 3 weeks ago, they thought he was younger than he is (he's
small) and he was getting over a respiratory infection, so he was not as
rambunctious as he is now.

Suggestions for anything we haven't tried?

K.C.