Part 2, Chapter 9.2; Nora to an ill and unresponsive Einstein at the veterinary clinic
Watchers (1987)
Context: I thought of you as my guardian, Einstein… you taught me that I'm your guardian, too, that I'm Travis's guardian, and he is my guardian and yours. We have a responsibility to stand watch over one another, we are watchers, all of us, watchers, guarding against the darkness. You've taught me that we're all needed, even those who sometimes think we're worthless, plain, and dull.
Quotes from book
Watchers

Watchers is a 1987 suspense novel by American author Dean Koontz. Along with Strangers, Lightning, and Midnight, Watchers is credited with establishing Koontz's status as a best-selling author.
Part 1, Chapter 7.7; about the death of Travis's landlord, Ted Hockney
Watchers (1987)
Part 1, Chapter 7.8; Garrison Dilworth on the responsibility to help keep Einstein free
Watchers (1987)
Part 1, Chapter 7.8; Garrison Dilworth reassuring the Cornells during their flight
Watchers (1987)
“Did you get the leash on him yet, Einstein?”
Part 1, Chapter 7.6; Nora's query during Travis's futile struggle to leash human-smart dog Einstein
Watchers (1987)
Part 1, Chapter 7.5; Nora's comment on her changes since meeting Travis
Watchers (1987)