(CNN) -- Michelle Knight wasn't the only one being held by Ariel Castro. But she knew she was different.
"I was the punching bag."
And she took it -- day after day, month after month, year after year. The terror and torment lasted from August 2002, when Castro lured Knight, then 21, into his car with the promise of a new puppy, to May 6, 2013, when she and fellow captives Amanda Berry and Georgina "Gina" DeJesus finally tasted freedom once again.
Speaking to CNN's Anderson Cooper, Knight describes being chained to DeJesus, of being threatened with death if she didn't deliver Berry's baby alive and of screaming until she lost her voice in the 1,400-square-foot, two-story home on Cleveland's Seymour Avenue.
What she never lost was hope. After being starved, chained and repeatedly raped, after being brutalized physically and humiliated psychologically, Knight said that she actually got stronger.
It might not have helped her in Castro's eyes, but Knight stayed defiant -- so much so that it became a source of pride.
"All my life, I was made to feel insecure, like I was worthless," she recalled. "And for the first time in my life, I stood up to a person that was a demeaning person."
"And it felt good to stand up for myself, (because) I never did before."
Sensed Castro was behind other abduction
One year later, Knight is in a very different place. While Berry and DeJesus have largely stayed out of the public eye, Knight has done the opposite -- appearing at public events and writing a book, "Finding Me," in hopes that her experiences will help people know they can survive anything.
Castro, the daily devil in these three women's lives for so long, is now out of the picture.
Arrested shortly after Berry and her then 6-year-old daughter escaped to a neighbor's house -- which led directly to the freeing of both Knight and DeJesus -- Castro killed himself in custody last September.
Before last May, neighbors had known him as an affable guy who'd wave or eat ribs with them on his porch. For years, Castro drove children around in a school bus. He jammed with fellow musicians in salsa bands.
But none of these people -- not even his closest relatives -- knew Castro's deep, dark secrets.
Knight was the first such secret, having accepted a ride from Castro after leaving a Family Dollar store in the northern Ohio city.
Nine months later, he took Berry as she walked home from her job at Burger King on the eve of her 17th birthday. Knight said when she first saw TV reports of this latest abduction, her first thought was that Castro was responsible.
While the two didn't interact much -- according to Castro's rules -- Knight said that Berry got better food, blankets, "basically whatever she wanted except for home."
"He had a fascination with her, more than me," Knight recalled. "She was the wife-type person. I was the punching bag."
Didn't speak out because 'I didn't want to get shot'
In April 2004, Castro nabbed DeJesus shortly after she was last seen with his own biological daughter, Arlene, at a pay phone.
Knight and DeJesus, all of 14 at the time of her kidnapping, became close in more ways than one.
They were chained together by the feet inside a small room. And they leaned on each other emotionally as well.
"When we were sad and got knocked down by things that he said, we would tell each other, 'It's OK, ... one day day it will be over,'" Knight said. "We (tried) to encourage ourselves to keep hope that we would go home, even though sometimes we didn't feel like they were."
There was no roaming the halls, no freedom without a threat.
Knight remembered going outside once and seeing other people. But she didn't dare speak up, knowing that Castro had a gun on him "everywhere he went."
She said flatly, "I didn't want to get shot."
'At least I'm still alive'
That threat was never more real than when Berry went into labor with Castro's child. Her paternity was later confirmed by DNA tests.
The baby girl was born into a plastic tub to contain the afterbirth and amniotic fluid. But she wasn't breathing, said Knight, who had helped deliver the child.
"At that point in time, I knew what he said: 'If the baby didn't come out breathing, I'll kill you,'" recalled Knight.
Berry's baby delivered by another captive
Throughout her harrowing ordeal, Knight said she coped in part by remembering her own child, whom she'd given birth to at age 17.
She told Cooper that she'd write songs and poems to him, among other musings "about what happened to me (and) things that I never had, things that I wanted."
And Knight worked, as best as she could, to find something, anything positive to hold on to.
"I (would) take myself outside of myself and look at a brighter side: At least I'm not dead yet," she said. "At least I'm still alive and breathing."
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Anderson's conversation with Michelle Knight continues Wednesday. Watch Part 3 of their interview on AC360, 8 and 11 p.m. on CNN.