He goes to check his bag. "I've got... enough devilroot for a fairly nasty bad-luck curse on one target or a small-scale demon-summoning, that can be for information or to set loose on your enemies or what have you. Not sure if I can summon into here, though, so you might be stuck with the entropy curse. There's some sage that'd be good for an exorcism, but you're probably not plagued by any ghosts. Unless you've got ghosts here, in which case, good news, sir! If you don't, it's probably better used on some chicken. If you've got chickens here. Hell, I don't know if you've got animals. I'd miss steak, I think. Let's see, witch hazel, that's good for a more potent ward, good amount of vervain, you could use that for healing or luck or cleansing negative energy, aaaand this shiny rock I found. I'd like to keep it, if I could, sir. It's useless, and I'm sure you've got shinier rocks, or could get them." He hauls out the puppy dog eyes.
And, incidentally, he's not thrilled about the idea of a nigh-indestructible Fairy Creep. Who could have guessed. And he doesn't really feel the need to mention that he can make artifacts without his anvil; why would that be relevant? (He remembers Belinda's legalistic oath-training very well; she spent a year and a half on it, and was an absolutely merciless tutor. Lies of omission aren't technically lies, and while finagling of that sort might be forbidden under the "no finagling" clause, the clause specified "forgetting to put something on this list". The list was of activities; this implies, logically, that the clause was about putting some activity on the list, such as "no drawing dicks on the ceiling" or "no putting hydrochloric acid in my shampoo". "No lying to me by omission" would certainly be an odd thing to include on that specific list, and can hardly be referred to as "forgotten". Coincidentally, this renders that clause damn near useless. Not that he's going to point that out. Doesn't seem particularly relevant at the moment.)
"I could probably make a replacement anvil out of enough gold and silver, but the one I have back home took me seven years, sir."
"I'll live... four hundred years, maybe five, given good health. Humans live about ninety years, but wizards get a lot longer, for some reason. And if we survive an injury, we heal all the way, no scars or anything. No quicker than a human, though. Still, it's nice."
Best way to avoid being stolen away... "Kill whoever tries" is the obvious, but he's not sure how the fairy legal system goes, and like hell is he going to have himself ordered to murder innocents, especially helpful ones. He helpfully assumes that his beloved master would be arrested, conveniently forgets to ask him about the probability of that, and discards this as a terrible idea.
"Stop hearing anyone who tries"? Has potential, but it seems too genuinely effective. Plus, if there were fairies running around who he just couldn't hear, he might not be able to effectively protect his beloved master! He shudders theatrically (inside his head) and washes it from his mind.
Pouting slightly, he says, "I'm sorry, sir, I just can't think of anything that would work. I'm not very good at this logic-puzzle stuff." Especially not on the scale he's using, which includes Mab and his erstwhile mother. He's a rank amateur in this arena, really.
Ah. If gilding his cage is the order of the day, then Ari can work with that. "Well... I'd like to keep up with my magic practice, sir. Under supervision, of course. And if you have novels here, then it'd be really nice if I could get some of those, because I only have a few paperbacks in my bag."
...Well, that's not technically true. But the potential harmful consequences of looking cute don't really bother him as much as they would most people. Not like this is the first time he's been captured in some way by an evil pretty fae, and this one doesn't seem inclined to chew on him first, so it'd be hard for it to be the worst.
"We probably want to go outside for the magic practice, sir. Most of the stuff I do is combat-focused, and it can get kind of heavy on the collateral damage."
"Uh... more than there is in here, sir. Some of my forms are designed to kill anything in a twenty-foot radius. I mean, I could probably create an underground cavern that would suit? It'd take a few days, but earth is my specialty, and I've got enough architectural stuff under my belt to make it stable."
"Yes, sir. I'll just pack the dirt into itself instead of pushing it out of the hole, it's a bit slower but it's better technique anyway. And avoiding water's easy, you can see through ground you're working with almost as far as you can through air. I'll want to map it out beforehand now you mention it, though."
Planning, planning, planning. He's got a notebook in his bag, he takes it out and readies a pencil. Then he rethinks this, and takes out a sack of chalk dust instead. "I need to map out the surrounding earth before I figure out where I'll put the cavern. I could just look at it magically and sketch it on the paper, but that's boring and there's not much reason not to just do the whole thing by magic. So instead, I'm going to make a scale model of the earth for a few hundred feet around here with chalk dust! Can I draw some rock out of your floor, sir? The alternative would be to go out and get a clod of dirt, but I can put the rock back afterwards, and you didn't want me going outside."
Ari smoothly scoops up a handful of slate from the floor and shapes it into a ball. He draws a circle around himself with the pencil (perfectly even, from years of grueling practice under Belinda's mathematically exacting eye), opens the bag of chalk, and holds the stone between his hands. He closes his eyes and begins chanting in a tongue that might be of some kind of Germanic or Nordic root; his words translate to a sort of mantra, demanding that the stone reveal the secrets of its earthy kin. It's a bit repetitive. After a few minutes of this chanting, the stone glows between his hands. Chalk fountains from the bag and hangs in the air, outlining... something, presumably the subterranean layout of the area. Ari opens his eyes, sets the rock down gently, and starts humming at the chalk thoughtfully. He prods at it occasionally; the chalk clings to his finger when it goes through the outline, then springs back into place when it's removed.
Eventually, Ari makes a fluid gesture and snaps "Blähen!", which causes the chalk to stream back into its bag accompanied by a localized breeze. He pushes his stone back into the floor, erases the graphite circle with a quick "Gehen!", and turns to the fairy. "I know where the cavern should go, sir. The next step is figuring out the circle and the incantation I'll need for the ritual, which will probably take a day or so if I don't do much else. And the ritual itself will take a few hours, and should be pretty impressive, I think."
"Very kind, sir," Ari says. "I am a bit hungry now; magic makes you hungry and tired, and that was just a little bit but even so. Could I have some food, please?"