Ah, it's for disputing transactions? Then it's fine (or at least, the best she's going to get). She does need to know how she can authenticate herself to them in the future, especially at other branches.

Tanya signs on the dotted lines. They won't pronounce her name quite correctly, but given that it's a heavily mangled Russy name to begin with, she doesn't really care.

Then Tanya will be issued a small leather-bound booklet with the bank's name and coat of arms on the cover (a pair of crossed ring inside a triangle), which she needs to sign a few more times at various points on the first few pages. The rest of the passbook is a blank ledger which will be used to replicate every transaction with this account. The passbook is a necessary but not sufficient proof of identity, and if anyone shows up at the bank claiming to be Tanya von Degurechaff in need of a replacement passbook because the current one is lost, that person is not going to get one without undergoing invasive questioning. If Tanya has any magic that might be helpful here – a way to indelibly mark something as her own property, or a way to make small objects unlosable, perhaps – the bank will happily accommodate her.

She can't mark any objects but she can demonstrate her flight magic which shouldn't exactly match anything around here, do they think they can identify that magical signature? Tabya is assuming they don't have a way to copy and spread around her personal mana signature, or they'd have said.

The bank teller casts a spell to observe Tanya while flying. After watching her for about thirty seconds his expression slides from detached to disturbed.

"It is very unique, no? I have never seen its like in all my life. Any learned Abadaran will recognize this spell, once they know the trick of it."

… yes, if Tanya is prepared to demonstrate this spell every time she comes into the branch, this exact spell and no other, the Triangle Gate Bank of Sothis is prepared to accept it as authentication. He will make a note of the relevant details.

And that's it! Does Tanya have any other questions for him before he goes to finalize the records?

Identifiying spells, and sharing updates so others will know to recognize them, is a core requirement for military mages. In a world where non-military spells are routinely cast directly on people, that must apply to everyone.

Yes, she can demonstrate it every time. (...unless something happens to her orb and she needs access to her bank account to, uh, continue living. But she can prepare for that when she knows more and has some actual plans.)

...she can demonstrate it every time, but might want in the medium or long term to replace this form of identification once she is more acclimatized. She understands that will involve detailed checks and maybe a fee or something.

Tabya has no further questions related to opening the account! She will have unrelated questions later that should probably be directed to someone else.

"Nazir and Hurayra are busy," Iomedae says abruptly. "We should find you lodgings in the city, unless you have magic for it, and someone to sell you Share Language each day until you no longer need it. Twenty scarabs is highway robbery."

That's the price you pay if you want to buy spellcasting on demand. The teller doesn't say this; basic economic truths rarely soothes angry customers. He gathers Tanya's paperwork, extinguishes the light on the desk with a wave of his hand, and bids them a polite farewell.

"Iomedae, right? Thank you for your presence back there." Tanya hadn't missed the glares, and now the intent is clear too: Iomedae thinks they're overcharging her. (A very bad thing to learn about one's bank where one has just deposited a large amount of money! She hasn't seen any schedule of fees, she assumed the fact the deposit didn't earn an interest would cover that, but maybe she should have asked?) 

"Did the Share Language not have a listed price? I couldn't follow Nazir's conversation before it was cast, obviously."

Should she trust Iomedae though? Well, she's here by Nazir's recommendation and Iomedae works with or for Nazir, so Tanya might as well go all in m; if they had any nefarious designs they could have executed them already. She'll spend her time for the foreseeable future learning about this new world and country (and eventually other countries too) and it shouldn't matter much which hotel she happens to pick for the first few days.

"I don't have magic that replaces lodgings." (How would that even work while she's asleep?) "My immediate concern about picking lodgings is security. I don't know if that's at all appropriate here, or what the threat profile might be, and the appropriate defenses. As a soldier, I'm used to operating in groups and sleeping under guard when necessary."

"My pleasure," she says warmly. "Abadar's men are, hmm, meticulous and fair, but not always scrupulous. He said it would cost twenty scarabs, and Nazir agreed on your behalf… we can find better prices elsewhere though. When I learned Osiriani I paid fifteen scarabs a day to a man from Oldstone, and I know I could've bargained it down to twelve."

And they can head out! Triangle Gate is another city district made of sandstone and sand, with even more aggressive use of water features and street trees. The heat is sweltering, but nobody outside in the afternoon is foolish enough to loosen their robes.

"This is not my favorite city, but it is not famous for public unrest," she continues. "If you fear strong enemies you would be safe in the pharaoh's palace, or perhaps the Pathfinder lodge, but the price is high. Mages often sleep inside an extradimensional space – permanent ones are feats of legendary spellwork, but temporary ones are not – and rely on their own wit during the day. I take it you have no spells like that? You can buy them, they are not much more expensive than Share Language. That will protect you from the man on the street who thinks you an easy target."

Tanya has no spells that would directly cool her down. She can make mirrors to reflect the sunlight and most of the heat radiated by the stones, but she'll still be breathing hot air and unable to radiate her own body heat effectively. The desert campaign had them flying at cooler altitudes, but they still had to carry a lot of water, and took dips in the ocean whenever they could get away with it.

...'Abadar's men'? Isn't Nazir one of those?

"I'm not familiar with extradimensional spaces, how do they affect security? Do you need a special spell to enter one, some kind of key? I don't know that I should fear anyone; I have no enemies here unless some of the dragon's friends want vengeance. I certainly hope this place is peaceful and law-abiding enough that I should have nothing to fear!" 

On Earth, if Tanya had somehow ended up in another country and at the locals' mercy, they would certainly have wanted to confiscate her orbs for reverse engineering. Laws don't stop a government acting in its national security interests, and Osirion doesn't need to worry about its diplomatic standing with Germania... Unless Nazir is right and Tanya is going to be abruptly sent back to Earth, in which case Osirion should be interested in possible trade (or else confiscate her orbs before that happens).

Obviously she's not going to point out that they might want to rob her, and it's very much to their credit if they don't (but she hasn't spoken to the relevant parts of the Osiriani government yet). And any security a private person could buy wouldn't help against the government. Tanya can probably go to a regular hotel, it's just that she's mentally out of practice going to sleep without considering her security situation.

And it looks like she lucked into a windfall that would let her live comfortably for a long time as a humble private citizen. Which is great! She doesn't plan to sit around unproductively, but it will take her a long time to learn enough to commit to any specific plan, and now she doesn't have to hurry.

"What's your relationship with Nazir? Do you work for or with him?"

She does look like she's overheating. Iomedae will stop at the next temple that isn't run by cheapskates and get some water.

"The spell is called Rope Trick, and it is a much simplified version of a far more powerful spell. It can be accessed physically through a hole torn in the air, but only eight creatures can be inside of it at once. If you enter with seven mice in your pocket, no one can follow you. It is a place not of this world, and some spells cannot reach it even if the hole is very near. Rope Trick is a rudimentary defense against an enemy mage Scrying your location in secret and teleporting on top of you as you sleep, when you are least able to defend yourself."

Tanya thinks to fear Ymohrglas even when he is dead. Wise of her. They did not capture all of his allies in the aftermath of the battle, and surely his friends and family will hear of his demise.

"Blue dragons are usually lawful. You are more likely to hear from lawyers than assassins. I would be on guard for enemy divinations, if they think to look for you, but this is only common sense. Osirion as a whole is very lawful, though whether the law is kind to you is another matter. I am not sure what would be most surprising to you, but as an example: slavery is permitted here. The pharaoh disapproves of slavery, of course, and the welfare of slaves is taken seriously in Osirion, so I will even believe him when he says this. But in Osirion, a law to be rid of slavery is a law that deprives slaveowners of their property, and so they must be compensated. For reasons I do not fully understand, the government either cannot or will not do this. So men are still enslaved for their crimes, and when foreign slaves flee their masters, it is the law that returns them. I do not know if this is surprising to you, but there may be some similar degree of surprise you ought to watch out for." Iomedae would have lead with 'Osirian women generally do not have bank accounts', but female mages are used to being insulated from the treatment often due their gender.

"Nazir and I are partners, along with a few others. We have been working together for nearly our whole adventuring careers. When we incorporated we decided that equal shares were the only way to avoid sour argument, but if anyone is in charge, it is Nazir." She sounds fond of him. "We assigned ourselves more traditional combat roles, back then, but today I wouldn't say he or I have one particular position on the team."