"You don't have to stay if you don't want." Even if he would very much like to make sure this kid is well fed and rested and such like. "But we have eggs and can set you up with a bed."

"What do you want out of it."

...it's a fair question. "I don't want people starving if I can help it."

She shrugs and has a face easily readable as "oh, one of those."

"I would like a bed."

Hey, there's a lot worse things than being a soft touch.

"We have beds." If there's not enough beds once the students arrive, he will work something out.

The eggs have disappeared. 

"You don't look like the duke."

"I'm not, I'm just a doctor borrowing his house."

"...what's a doctor?"

"Like a healer. Or a herbalist."

Her eyes widen. 

"I'M NOT GOING TO SELL MY TEETH."

Oh dear. "I don't want your teeth. I'm not going to do anything to you that won't make you, personally, better."

She looks at him suspiciously. "...better because I have more food and less teeth and this leaves me better off on net?"

"Better off because you have food and all your teeth." Unless something goes very wrong, but he's not a dentist so hopefully that will not happen.

She looks at him. "I'm not sick."

"...she is definitely extremely sick, street kids always are."

"Not having enough food, especially if it makes you faint, is a kind of sick."

"No, 'sick' is when you cough a lot and then get sores all over and then die."

"That's an infection, which is-- a category of sick? But not eating enough will also kill you."

"Not all things that kill you are kinds of being sick! If that guy over there stabbed me it wouldn't be being sick."

"That's true! But the problems caused by not having enough food are more like the problems caused by having an infection than being stabbed."

"...should you give her some kind of examination?"

"Only if she's willing to let me." Look at this non-terrifying doctor who doesn't want to steal your teeth.

"...I want a copper piece."

1. Is that a lot of money?

2. Does Tanidio have a copper piece on him?

3. Can he communicate this purely through facial expression?

He hands her a copper piece. "Let Dr. Bun take a look at you."