Cale, through some failure of magical shenanigans, becoming half cat. Like, cat ears and tail, but not actually a cat beastkin.
It was supposed to turn him completely into an animal and reduce him into nothing but a mindless creature, but bro is so full of ancient powers and stuff, that wasn't gonna work. It wasn't fully ineffective though, so now he's a catboy (catman?) for a bit.
At first, they don't really notice much of a difference between his usual self and his current part cat self. He looks as haughty as ever, with the fluff of fur where his human ears were leading up to the large red ones on his head that looked, frankly, quite majestic alongside his long-furred tail. His ears and tail twitch and shift outside his control, showing his emotions much more than his expression ever would, but otherwise, there's not much more to say than that.
Except, they start actually looking at what his cat parts are saying.
For one, even when he is lounging lazily, his ears are almost always pointed in their direction. He's very often paying attention to them or at least using their voices as background ambience.
His tail swishes calmly whenever he's listening to them. Especially the children. It shows that he's not just attentive, but very content, even enjoying himself.
He doesn't suddenly get more fastidious about himself getting wet or dirty or anything, but he does start brushing up against people.
It appears to be an utterly unconscious move on his part when he first does it, pushing against Choi Han for a moment before moving past him. On and Hong immediately stiffen, eyes wide, and Ron also raises a brow, though the others don't catch on yet.
On briefly tests her theory, walking up to him and leaning against him in her human form while he's talking to Rosalyn. Without batting an eye, a long red tail brushes around her and he rubs her head, easily leaving his scent on her just as easily as she's left hers on him.
Then, as though to punctuate their discussion, he leaves his conversation with Rosalyn off with a parting flick of his tail around her leg and a light brush past her as he walks in the opposite direction. Not enough to shove but enough to put his weight lightly against her. It would've been odd had Rosalyn not had the context On so kindly and silently provided, leaving the witch feeling very much chuffed instead.
(This was also a surprise to Alberu, who ended up with Cale deciding that his head looked like a great place to put his own. Which is exactly what he did when looking at a paper the prince was about to show him, the redhead basically draping himself all over his back.
"Dongsaeng."
"Yes, your highness?"
"Pray tell, what are you doing?"
"Reading."
"Does that require you to use your beloved hyung as furniture?"
"No, it does not."
Cale didn't move for another five minutes.
Alberu didn't have him move despite his complaint.)
Even Ron gets the treatment.
It's cautious, as the man always is with the assassin. And he's never been particularly touchy with him or Beacrox. And yet, Cale finds himself holding something being handed to him a touch too long, his wrist able to rub against the Molans in a way that seems to calm him, judging by the little satisfied narrowing of his eyes when he does it. Cautious and tentative, but still wanting to do it. The Molan patriarch and his son notice it. Neither say anything. But, if Ron adds a little honey into the lemon tea the next time he makes it, well, that's neither here nor there, is it?
...
Also, Cale purrs easily. It doesn't take much for him to feel happy or pleased.
He's embarrassed by it, but Cale grows to just deal with his overactive motor.
One trigger is Beacrox's food. He likes tasty food, after all. Just a whiff of its scent has him purring in anticipation of the taste, especially if it's meat (cats being obligate carnivores has indeed increased his meat intake).
Another is when the kids are talking to or around him. Watching them having fun, enjoying life. Sometimes, they'll just be yappin, and all of a sudden—prrrrrr. They'll look over and see Cale covering his face with his hand.