Ultima is from the village Las Pasturas, where Tony's father comes from and where Tony was born. She is old now, and, having no family left, is living alone when Tony's parents bring her into their home in Guadalupe, a town a few miles away. Tony's parents open their home to "la Grande", as they respectfully call her, because they feel "it is not right that (she) be alone in her old age", especially since she has served others all her life (Uno).
I think there is no doubt that Ultima feels safe with Tony's parents. She "slip(s) easily into the routine of (their) daily life", and is beloved by all the members of the family. Ultima's sense of security, however, is not dependent upon her environment; she possesses a deep tranquility of spirit which enables her to remain serene anywhere and under any circumstances, even in the face of danger and death. Confident that "the smallest bit of good can stand against all the powers of evil in the world", she unflinchingly confronts evil personified and cures the sickness of Tony's Uncle Lucas (Diez), and even in death, Ultima is secure with the knowledge of her "bond to the time and harmony of the universe". Ultima bestows upon Tony the gift of her peace when she dies, blessing him "in the name of all that is good and strong and beautiful", and counseling him to "always have the strength to live (and) love life" as she did (Ventidos).
Before coming to live with the Marez family, Ultima lived in Las Pasturas, a small village in the llano. The llano is where Gabriel, Tony's father, is from. When he married Maria, Tony's mother, they lived in Las Pasturas. Because Las Pasturas is somewhat isolated, Maria was very lonely when she lived there, and Ultima befriended Maria, even helping in the birth of her sons. Ultima is older now, and Maria feels she shouldn't live alone in Las Pasturas and that it's their duty to take care of her.
Ultima is a curandera, a healer who uses herbs and other ancient remedies. She's respected by those who understand her powers, but she's feared by those who don't understand. Ultima feels safe with the Marez family because she knows they truly care about her. She also has powers that allow her to feel secure no matter where she is. She becomes Tony's mentor and helps him to understand his dreams.