Marian is DEFINITELY NOT crying into her tray of creepy magic school cafeteria food that someone kindly brought her, she just...has allergies, or something, yeah that's probably it... 

She scrambles up, dabs her eyes on the sleeve of her scrubs, and goes to open the door. "Yes? Do you need medical attention?" 

"I will trade wards on your office for medical training."

"I don't like doing this. He going to die," Jin Zixun says in significantly worse English.

Marian lights up at the mention of wards, then droops a bit and glances between the two of them. This seems...awkward? She's clearly missing some backstory here. 

Eh, whatever. 

"Wow! Uh, what kind of wards, how long will they last - this other kid did one on the door but he said it wouldn't last very long...?" 

"Zixun's wards are very good. He'll update them as needed, as long as you teach me."

"For two weeks until you die!"

...Marian looks between the two of them again. This is agonizingly awkward but it seems important not to make agreements with people when she's clearly missing gigantic chunks of context. 

"Uh, you two seem to - feel differently about this?" she says uncertainly. 

"Sorry, I'm the favorite of the, uh, leader? Of the Shanghai enclave? Zixun is an asshole who likes making people upset but I can in fact tell him to do whatever I want. And what I want is to learn medicine."

"Well, that's a good idea and I'd be happy to teach you! Uh, is there an - urgent reason for it? Just wondering if I should prioritize a particular area when I decide what order to explain things in." 

"The school doesn't have the biology classes. My affinity is healing. I'd like to learn to heal without magic so I don't have to use the mana for everything. I think also that knowing more about the body make inventing healing spells easier."

"....The school doesn't have biology classes? Man, that sucks. I guess it's not the priority if you're magic but still! Anyway, yeah."

She glances around. "Fortunately I don't even have to try to ask the void for this, my infirmary came with one book and it's Gray's Anatomy." Marian goes and retrieves it from the shelf. "So. About where are you at now? I mean, uh, do you...know that bodies have organs, and stuff?" 

"The previous nurse taught me some thing. I know about the vital signs and the bodily systems and the first aid."

"Oh - so you're not freshman students then." Which bodes well for her wards! "Right. So - hmm, we're going to want to cover treating injuries more than illnesses, I guess? Since it's just kids here, none of you are going to be having heart attacks. Hmm - if you've done basic anatomy and organ systems, maybe we should start by covering some physiology background, and that'll cover a lot of background on what drugs work to treat different things?" 

"Yes, I am interested in the drugs. --Zixun, do the wards."

He mutters something extremely irritated in Mandarin. 

"Drugs, I think, have the effect that the spells have? So I will be able to better work with the body's expectations."

"- Huh! Yeah, that makes a lot of sense, I guess." To the extent that ANY of this makes ANY sense. It's literally magic. 

She flips to the index of Gray's Anatomy. "Uh, right - do you know about cells and what's in them?" 

"I have a spell that lets me look at the cells."

"What? Whoa! That's amazing, I'm so jealous! ...Uh, anyway. I don't know how obvious the structures are, so - let's look at this diagram?" 

An antique copy of Gray's Anatomy is not the best source of detailed and clear biology diagrams, but Marian manages to find one of a cell. "Right - do you know what the different bits are here?" 

Wen Qing will in fact summon an illusion of her own cell and compare notes between it and the diagram. 

That's soooooooo cool! 

"- Uh, I - that's confusing, sorry, I think this is a plant cell - it says 'cell wall', animal cells don't have that and I think don't have vacuoles either, just a membrane. But the cytoplasm and nucleus are all right - here let me look at yours, maybe I can just draw it and label the bits..." 

Marian is not the world's best artist, but can label a very oversimplified diagram that has the right bits for an animal cell. 

"So, uh, do you know what mitochondria do?" 

"They are the powerhouse of the cell! I hear the Americans make a joke about it."

Marian giggles. "Well, that's one way to find that out! Yeah, they make energy, basically. It's called 'cellular respiration' - respiration is another word for breathing, in English, I think that's the name because the main kind uses oxygen? In animal and plant cells, most of that happens in the mitochondria, which we think used to actually be some ancient species of independent cells, that sort of - invaded another cell or got eaten by it, but ended up just living there? They've actually got their own DNA - uh, genetic code, how heredity works? And it's only passed from your mother, because sperm don't have mitochondria, so it lets us study populations based on figuring out the last common maternal ancestor. ....Sorry that's kind of a digression, mitochondria are just really cool." 

"Mitochondria are very cool! I wonder what would happen if I asked the void for mitochondria spells. This one I learn when I ask the void for a spell to teach me medicine."

"Uh, this is a horrible death school so I'm kind of worried it'd give you, like, a spell version of cyanide? ...That's a poison that kills you almost instantly, it fucks up the mitochondria and prevents your body from using oxygen to make energy."