Look at the new Berwynn if you want an example
While I don't exactly dig new Berwyn compared to the old one, old Berwyn could also flip flop between sub and dom. Also the only character like that.
MAYBE you could make a case for Lyric even though male/female/futa Lyric is still just raw hero worship.
You can't exactly call Zo, Oma, Agnimitra, or Kaliani malleable.
Agni's got other issues. 10 variations isn't one of them.
But what I more want to talk about is
Sounds like you want to create your own character for you to fuck.
So assumedly we've both played and interacted with the community of CoC1.
People weren't off about Amily who had two states or Jojo who had three states. Sophie's with her two and technically Kelt's two.
Arian's entire relationship arc is that they end up willing to go to lengths to be the kind of person the PC could be physically attracted to.
Malleability isn't diametrically opposed to identity. It's how well you sell the idea of believability of the various options said character could undergo that helps to establish identity.
e.g; You don't just flip a switch on Amily, you have to force that change onto her. Arian has to go through an entire relationship arc just to reach the point where they feel comfortable making their decision.
That said, I still disagree with the notion that this content should have been with two established characters. Content exclusive to group sex? No yeah I'm sure they're well aware of how that'd pan out if it was stapled onto individuals people care about.