Julia M. is the wife/partner of Henry.
She meets him in a bar in Boulder, CO, in 1975 while Henry is drunk. He introduces himself and they hit it off. After getting married and a dog, Julia gets a job request at Yale University in Connecticut. However, she becomes increasingly unable to think straight, and it is revealed that she has early onset dementia, or Alzheimer's. Having been forced to leave her job, depending on your choices her family will either fly to the United States from Australia and take Julia back home to Australia or be sent to a nursing home in Boulder.
Julia is referenced by Henry many times within the dialogue of Firewatch, usually when Delilah asks him questions about her.
In a nighttime daze, Henry calls Delilah thinking it's Julia. Delilah picks up, only to hear Henry muttering in his sleep.
- Originally Julia was supposed to be American and not Australian.