You decide to be honest with Altria.
Gained Honest F+
"I can't say what the old man's intentions were," you tell her as you get to your feet, "but as far as I can tell, the seal won't inconvenience me in any way."
Most of the people nearby look puzzled at this. "What do you mean?" Altria asks.
"Simple." You shrug. "I don't use external sources of magic to power my spellcasting. No gods, no demons, no ancestor spirits; it's all me, and only me." Well, you and your past life, but that's just quibbling. "Unless there's some other function to the seal that I haven't noticed yet, it won't interfere with the way I use magic at all."
"Then what was the point?" Cordelia asks.
"I think Ambrose may have mistaken me for the usual brand of sorcerer," you reply. "The ones who can barely levitate a pencil with their own power, yet can fly and throw around bursts of fire when they invoke their patrons. And we do live on the Hellmouth, Cordy. People who go looking for magic there are pretty much guaranteed to find the worst possible kind, assuming nothing eats them first. I can understand why Ambrose would have wanted to keep me from getting mixed up with that - which doesn't mean it wasn't a dick move on his part. He could have asked permission first, or at least explained what he was doing."
"Ambrose has never asked permission for anything, in my experience," Altria sighs. "He simply acts as he likes. What is truly irritating is that, more often than not, his decisions turn out to be correct."
"Well, this time he misread the situation," you say. "On that note - would you mind not telling him that I said any of this? I'd rather not have him decide to come back and bind my magic completely."
The blonde frowns thoughtfully. "I can certainly agree not to broach the subject with him," she replies. "If he asks me directly, however, I would prefer not to have to lie to him. Annoying as he is, Ambrose is my teacher, and a friend."
You nod slowly. You can certainly understand where Altria's coming from with that. On the other hand, this is your power and safety potentially being put at risk - and you note that she didn't say she wouldn't lie on your behalf.