Ask her how you can know she isn't infected.
From Create Your Own Story
"How do I know you aren't infected though?" You ask. "I mean, I've seen with my own eyes that it takes a couple of hours before it really kicks in."
She turns and looks to you, perking a brow. "I could ask the same about you," she says.
"And I think you should. We can't really just go around trusting people if things are as bad as you say. Or I've seen."
"Well, you got some kind of idea?" She asks.
