...He casts an Aura Sight. It probably won't tell him anything he doesn't already know, if she's got a really surprising aura it would be dangerous to walk around with it showing, but it seems like it can't hurt.

He's not wrong: she reads faintly Evil, neither Lawful nor Chaotic. 

Well.

She could just be a Neutral Evil dabbler of some variety, in which case the best response depends quite a lot on the details of what kind of dabbler.

She could be an Evil cleric of a Neutral god. Nethys is the obvious choice for a wizard, but it's not impossible in principle for it to be someone else. If that's the case it's probably worth trying, carefully, to make contact with her.

She could be a cleric of a Neutral Evil god. Norgorber, maybe, as Evil gods go it's relatively comprehensible why someone might be a Norgorber cleric. Urgathoa, if she's a very particular flavor of necromancer or alternatively the kind of wizard who likes to invent magical diseases. Maybe one of the obscure ones, there are kind of a lot of obscure ones, for all he knows there's a Neutral Evil god of Evil scrollmakers, this isn't actually his area of expertise.

It might be worth trying to make contact with a Norgorberite, depending on the Norgorberite. It... is probably not worth trying to make contact with an Urgathoan. 

(Does he have a way to tell? He knows Nethys's domains. He... is less sure of Norgorber's or Urgathoa's. Evil, presumably. But if she cast her domain spell it wouldn't show up to a Spell Gauge regardless.)

She purchases some presumably-less-displeasing apples and leaves. She takes a right turn down a deserted alleyway, and—

:Did you see the woman who just went into the shop you were watching yesterday?:

:Yes. What about her?:

:Could you follow her home when she leaves and tell me where she lives?:

A few moments later, a perfectly ordinary thrush lands on the roof of the bakery, carrying a piece of bread in his mouth.

It's going to be a long time, but eventually she leaves by the side door, around the same time as the previous day.  Two streets over, she goes into a loud building that smells like stale beer and tallow smoke.

The thrush is a very clever and experienced bird, though, and can tell that this is not the kind of building that humans sleep in (it's not tall enough to have rooms with beds like his friend's, and it doesn't smell enough like food).  It will take Great Dedication but if he waits a while longer, he can see her leave this building and follow her again.  Fortunately he can be fortified in his quest- someone has eaten most of a mutton pie and dropped some crust on the opposite side of the street. 

But it's less of a long wait the second time, and the thrush can follow her back down the street and to a different building, a tall brick one with a good almond tree for perching on.  It has a lot of windows, so it takes some careful watching to figure out which is hers, but soon he can spot a not-flickering light like his friend makes on the second floor.  She seems to have two rooms: one with a lot of books and some fruit and other tasty food, one with some more books and a bed and other nice soft nest materials, and a low fire in the grate even though it's plenty warm out if you have feathers. 

Crust and useful information! What a great day! His friend is going to be so proud!

:I don't suppose you remember Norgorber's domains?: He's given the group his summary of what he knows, and they're discussing what to actually do about it.

:Uh, Evil, and I think Trickery, and then I'd be guessing for the rest. Probably Death, that seems like the sort of domain Norgorber'd have. Trickery gives Disguise Self at first.: She only remembers because it's one of Calistria's.

She didn't have a Disguise Self prepared, but the absence of a Disguise Self spell tells them fairly little. 

:Did you pick up on anything else that would help us tell one way or the other?:

:Just that she was working at the scriptorium. We do know they're selling third circle scrolls, so it isn't very surprising for her to have an aura in her own right, and for a wizard Nethys is the obvious guess.:

Nod.

:But we'd be staking a lot on a guess.: She doesn't trust a Norgorberite not to try to find a way to blackmail them, if they thought they could get away with it.

:Can you read her mind at dawn to check who she's praying to?:

:She'll have a decent chance of throwing it off. I don't know how lucky I got landing the Spell Gauge.:

:And if she doesn't pray for new spells every day it might not even work.:

:I expect I could land a Message on her without breaking invisibility. Do you think that would be better?:

:...Depends what you said. It'd be hard to avoid it sounding like a threat or a test.:

He does also have Charm Person but he's not going to try to charm someone he might be trying to work with, that's unethical (even setting aside the logistical complications). :But it probably wouldn't be less threatening if we knew who she was a cleric of?:

:Probably not, yeah. ...It might be less scary coming from another secret cleric, but I don't get Message.:

:You could have Ruscello drop her a note.: Message isn't great at communicating tone but it manages to come across as deadpan anyway.

:Not actually less scary. And it might work as a scrying focus.: