"How about enchanting things? Like that thing you did with Sayaka's bat?" you suggest. "... say, what happened to that bat, anyway?"
"Hmmm... Good idea," Mami agrees. "And... I don't know. The enchantment would have gone away after a while, though."
The blonde makes no move to go anywhere, content to just lean her head against your shoulder.
"Uh, Mami?" you ask.
"Oh, um," Mami says. "I need a cup of water."
"Sure, let's go get one," you say, moving to rise. Mami leans insistently on you, though, shaking her head. She holds up a single hand, and you see a golden ribbon snaking away into the kitchen.
"Ooh, clever. You can't see what you're doing, though?" you ask.
Mami grins. "Are you sure?"
"... you can?"
The other end of the ribbon returns, a knot tied firmly around the handle of a teacup full of water, and another heavy knot of ribbon tied just beneath that. The teacup is borne steadily to Mami's waiting hand, and she dismisses the ribbon. "Here, watch this." She concentrates for a moment, a frown flitting across her face, and the cup morphs, golden filigree creeping across the white porcelain like living vines. You can see her magic twining around the cup and infusing it.
"OK," Mami says. "Enchanting things... took me a really long time to figure out on my own. I'm sure you won't take long, though!"
"Because I have a great teacher to help me," you fire back.
Mami blushes slightly. "Well, anyway, one of the first things I figured out was durability." She holds the cup lightly by two fingers, and then reaches up, inverting it over your head.
"Hey!" you begin to protest, jerking away before you realize that nothing's actually coming out of the cup, the water held back by a glowing barrier. Mami chuckles a little.
"Another thing is this barrier trick," she says. "I used it with Sayaka's bat."
"Cool," you say, poking at the barrier, which holds firm against your finger. "Is there by any chance a way of making something bigger on the inside?"
"There should be," Mami says thoughtfully. "I have no idea what happens if the enchantment runs out, though."
"Does it run out when it's out of magic or something?" you ask.
"Exactly," Mami confirms. "Watch, I only put a little bit of magic into the cup." She holds the cup upright, and as she said, the enchantment fades a minute or two later.
"Did you see how I did it earlier?" she asks.
You nod. "I think so."
"OK," she says. "Um." She raises the cup to her mouth and drains it of water before passing it to you. "I'm sure you'll do fine!" she says hastily. "Just... making sure, you know?"
"Heh, good thinking," you say, taking the cup. She lays her hand against yours, warm and soft.
"OK, try it now," she says.
You proceed to do just that, trying to twist your magic in the same way Mami did.
"No, Sabrina, not lik-"
The cup cracks in your hand, a deep split developing in its side.
"... whoops," you say sheepishly.
Mami laughs, before catching herself and choking back her giggles. "Uh, sorry, Sabrina, I didn't mean to laugh at you," she says, peering worriedly at you.
"It's alright, Mami," you say. "Really, you don't need to worry so much. And I'm glad you had to foresight to empty the cup first! So uh... what now?"
Mami shakes her head. "I practiced with rocks after my first, ah, accident, myself. You could keep trying with the cup? Since it's already broken?"
"Guess so," you agree.
You continue trying for half an hour, with Mami's gentle encouragement and corrections, the cup shattering into smaller and smaller pieces with each successive try, but to no real success so far.
"Don't give up, Sabrina!" Mami encourages. "You're getting closer."
"Mmmm," you mumble, sifting through the small pile of porcelain shards. "At least nothing's exploded yet?"
Mami nods in agreement. "I did that, the first time. The rock completely fragmented."
"Ugh," you say. An idea strikes you. "Eh... I'll leave this aside for now and come back another time? In the mean time, I have an idea - you have Tiro Finale, right?"