At the start of this conversation, Adelaide had no intentions of trying to pretend she kept being ignorant that Rodeo was the Dog King - she'd meant that she didn't know his title when they first reunited. But Isaac was presuming that ignorance had continued, and Adelaide decides on the spot that correcting his assumption is probably only going to invite complications, and so she keeps her mouth shut.
She doesn't know when, and she doesn't know how, but everything she knows about her brother, every feeling that has ever passed between the Hawkins siblings, tells her that she will not be left here to stand trial - whatever farce of a trial that Olinger might mock up. And so she only needs to get through this interrogation without completely screwing up, without doing something that will get her moved straight to La Quinta or hanged in the Rotunda on the spot.
Her expression is perfectly cool, collected, when he asks the next question, and her brows lift some. "Filing," she says, dismissively. "With the serial killer loose on the Medical Center, I lost both my part-time volunteering gig and my excuse to get out and see my family. So I found something else to do." She smiles, shrugs. "I like being useful." It's a lie, but who can prove it?