‘We Take the Crumbs’

On a piece of plastic no bigger than a cigarette lighter rested great hopes.

It was a Friday in late spring, and Ms. Quillen was about to join a conference call with one of the world’s largest parts suppliers. In the automotive food chain, big suppliers like Delphi and Johnson Controls constitute Tier One. They sell directly to the carmakers. D.E.P., which primarily sells to other suppliers, is in Tier Two.

“Tier Ones are eating whole peanuts,” Ms. Quillen says mordantly. “We take the crumbs.”

D.E.P. was trying to take some control over its destiny.

Ms. Quillen was proposing to make a new part used in the transmission of General Motors vehicles. It had taken weeks to design and fabricate a prototype. Now, the little part sat on a conference table in the Tier One’s offices outside Detroit.

Ms. Quillen apologized for dialing in rather than attending the meeting. But it was also true that her own office was where she felt most confident, seated at a large L-shaped desk. On her windowsill were two copies of “Lean In” by Sheryl Sandberg of Facebook. She had been reading the new Ivanka Trump book, “Women Who Work,” which she praised for “good information, good suggestions.”

She sees herself as a driver of people, as a manager who places great demands on her workers and on herself. Others could find her intimidating. On one of her two Dell monitors was a sticky note to herself: “It’s About Feelings.”

“I built a wall around myself,’’ she had said earlier, describing how she rescued the company from years of unprofitability. “If I had allowed myself to be vulnerable, you get hurt, and if you get hurt you start to lose confidence in your ability.’’

“It’s sad, but I became immune to people,” she said.

On the call, the Tier One executive, a woman, expressed interest in the part D.E.P. had designed, but said it would seek competing bids from other injection-molding companies, of which there were many. “It’s our policy that we have to market-test the part,” the executive said. “You’d be competing against other suppliers that have the same capability.”