He talks to her, while he's drawing the pictures, leaning on the vocabulary he's already provided but not restricting himself to it. Immersion was how he learned Iberiola.
Eventually, she interrupts the lesson by pushing the paper away. She looks him in the eye, to get his attention. She touches her legs. She points to the quartz crystal he used in his earlier demonstration of magic. She touches her legs again and mimes with her hands something jumping off them and fluttering rapidly away.
He frowns, considering interpretations, then draws a little stylized Jade-with-legs, and a little stylized Jade-with tail, and an arrow from the one to the other. "Your legs are going to go away? How long - how many days -" He sketches the path of the sun; they've already done numbers. "One day, two days, three days -"
Cymbeline hmmms. "Okay, so this is a temporary visit. I wish I knew what you wanted to get out of it..." He sighs and goes back to writing. Names, this time - himself, Zoyah, Kerem, Jade's temporary moniker.
After labeling her various drawings of Cymbeline with "Cym" (apparently his full name is too long to bother with), she repeats the legs-flying-away mime and this time leans away after her fluttering hand and grabs it and hauls it back. But when she attempts to stick it back onto her hip, it just keeps stubbornly fluttering.
She looks at him expectantly.
"Yeah, transfers do that if you don't catch them... uh... I guess they were expensive, maybe you need to trade it back..." He gets up, finds her a jar, and offers it to her.
Cymbeline is going over their past notes and what words they've covered, trying to figure out how to go forward in some kind of sensible order, when Kerem returns.
"I've told the King and Queen," Kerem reports. "And, I've found a book on sign language - I don't know it, but it might be easier for her to pick up and more portable than writing?" He offers Cymbeline the book.
Cymbeline flips open the book; it has a lot of prints of diagrams of signs and their meanings. He shows it to Jade.
"Is that better than learning to write, for you? I imagine drawings will still be useful, but there are advantages to this too, even though I'll have to learn it too..." He shrugs and starts doing his best to draw the concepts in the book for her, and studies the signs for himself.
She is particularly interested in verbs. As soon as she can string signs together to make a complete sensible thought, she does: I walk. (With a silent laugh.)
"Yes. Yes you do," Cymbeline laughs, after he's deciphered the signs. "Not very well, but then neither do I and I've had more practice..."
Cymbeline has a good head for vocabulary; he can go at whatever pace is comfortable for her. Eventually they've passed things like pronouns and "walk" and "sit", skipped over the sign alphabet which doesn't seem to interest her, and moved on to slightly more complicated words. Prepositions, nouns like "bird" and "fish" and various body parts, verbs that are a little trickier to draw or mime like "see" and "hear" and "want".
I want legs.
"Uhh..." He doesn't know how to ask 'forever', but - he can always take them off again, if she changes her mind, he supposes. "You want me to magic your legs on?" (They don't have a sign for magic covered, but it was mentioned earlier in the writing lessons.)
He blinks.
"These are -" They don't have "cursed". "These are - bad magic legs."
"You want these legs? They'll - they must have -" They don't have 'hurt', either; he pinches himself in the arm - "Ow, that hurt. These legs hurt. You want these?" He's not sure where you go to buy less cursed legs, but there's probably somebody selling, people make all kinds of bizarre economic choices, he could probably even pull her tail out from under the layering and swap it for someone who wants to be a merperson just like she wanted to walk.