How much a part of it? Just the tips, half his head, a small patch…?

Small patch.

Then magic on another.

Theo doesn't like his new hairstyle.

Eugh.

"Cute grumpy kitten: exhibit A."

"What?"

"Apparently I am a cute grumpy kitten, especially when I make an 'ugh' sound."

"Why?"

"Ask him." Eyeroll.

"It's because he's really adorable when he doesn't like stuff, and he makes cute noises like 'ugh' and he sighs and he rolls his eyes. I mean, lookit him!"

"...I don't really see it."

"I mean, I wouldn't personally call 'ugh' a cute noise, just a regular noise, but okay."

"It's not regular! It's, like, occasional at best! Except when you're Theo, in which case it's regular."

"If you say so," he says, slightly dubiously.

He shrugs. "I don't say 'ugh' or sigh or roll my eyes or act grumpy nearly as much as you do."

"Maybe it's just a trademark thing of mine," he says, then starts– and stops rolling his eyes.

"Case in point."

"Trademark things aren't bad," he says, then pointedly does not sigh.

"I know they aren't, never said they were, I'm just insisting it's cute."

"Mmh," he agrees. "Okay. Yeah." Shrug.

"For the record, I'd like to register the prediction that the magical hair thing will wear off faster, if the nonmagical one will wear off at all."

"Did we time the previous thing? I mean, it'll be some data if it does in fact wear off at all, but it would be nice to check how long they take in relation to each other, too?"

"You have both types on your head right now, we can just wait and see whether they disappear roughly at the same time or what."

"… Right, yeah," he says, frowning again. "I swear I'm not usually this forgetful."

He pats Theo's head.

It turns out that Sadde is in fact correct, and the magically dyed patch of hair does start fading before the non-magically dyed patch.