After she returned from her own journey to India, Brennan visited Jobs at his parent's home, where he was still living. It was during this period that Jobs and Brennan fell in love again, as Brennan noted changes in him that she attributes to Kobun (whom she was also still following). It was also at this time that Jobs displayed a prototype Apple computer for Brennan and his parents in their living room. Brennan notes a shift in this time period, where the two main influences on Jobs were Appleand Kobun. By the early 1977, she and Jobs would spend time together at her home at Duveneck Ranch in Los Altos, which served as a hostel and environmental education center. Brennan also worked there as a teacher for inner city children who came to learn about the farm.
In 1977, Jobs and Wozniak introduced the Apple II at the West Coast Computer Faire. It was the first consumer product sold by Apple Computer and was one of the first highly successful mass-produced microcomputer products, It was designed primarily by Steve Wozniak. Jobs oversaw the development of the Apple II's unusual case and Rod Holt developed the unique power supply.
Jobs usually wore a black long-sleeved mock turtleneck made by Issey Miyake (it was sometimes reported as St. Croix brand), Levi's 501 blue jeans, and New Balance991 sneakers to work. He said his choice was inspired by that of Stuart Geman, a noted applied mathematics professor at Brown University. Jobs told his biographer Walter Isaacson "...he came to like the idea of having a uniform for himself, both because of its daily convenience (the rationale he claimed) and its ability to convey a signature style."
As Jobs and Apple became more successful, his relationship with Brennan grew more complex. In 1977, with the success of Apple now a part of their relationship, Brennan, Daniel Kottke, and Jobs moved into a house near to the Apple office in Cupertino. Brennan eventually took a position at Apple in the shipping department. Brennan's relationship with Jobs was deteriorating as his position with Apple grew, and she began to consider ending the relationship through small changes. In October 1977, Brennan was approached by Rod Holt, who asked her to take "a paid apprenticeship designing blueprints for the Apples." Both Holt and Jobs felt that it would be a good position for her, given her artistic abilities. Holt was particularly eager that she take the position and puzzled by her ambivalence toward it. Brennan's decision, however, was overshadowed by the fact that she realized she was pregnant and that Jobs was the father. It took her a few days to tell Jobs, whose face, according to Brennan "turned ugly" at the news. At the same time, according to Brennan, at the beginning of her third trimester, Jobs said to her: "I never wanted to ask that you get an abortion. I just didn't want to do that." He also refused to discuss the pregnancy with her. Brennan herself felt confused about what to do. She was estranged from her mother and afraid to discuss the matter with her father. She also did not feel comfortable with the idea of having an abortion. She chose instead to discuss the matter with Kobun, who encouraged her to have and keep the baby, and pledged his support. Meanwhile, Holt was waiting for her decision on the internship. Brennan states that Jobs continued to encourage her to take the internship, stating she could "be pregnant and work at Apple, you can take the job. I don’t get what the problem is.” Brennan however notes that she "felt so ashamed: the thought of my growing belly in the professional environment at Apple, with the child being his, while he was unpredictable, in turn being punishing and sentimentally ridiculous. I could not have endured it." Brennan thus turned down the internship and decided to leave Apple. She states that Jobs told her "If you give up this baby for adoption, you will be sorry" and "I am never going to help you." Now alone, Brennan was on welfare and cleaning houses to earn money. She would sometimes ask Jobs for money but he always refused. Brennan hid her pregnancy for as long as she could, living in a variety of homes and continuing her work with Zen meditation. At the same time, according to Brennan, Jobs "started to seed people with the notion that I slept around and he was infertile, which meant that this could not be his child." A few weeks before she was due, Brennan was invited to have her baby at the All One Farm in Oregon and Brennan accepted the offer. When Jobs was 23 (the same age as his biological parents when they had him) Brennan gave birth to her baby, Lisa Brennan on May 17, 1978.