Her scars -- from the 19 times she was stabbed on May 31, 2014 -- testify to that moment of betrayal. But, they also mark her incredible strength to survive.
"I've come to accept all of the scars that I have," Leutner said in an exclusive interview with ABC's David Muir. "It's just a part of me. I don't think much of them. They will probably go away and fade eventually."
Watch the full story with David Muir on "20/20" Friday, Oct. 25 at 9 p.m. ET on ABC
Leutner survived an attack that captured headlines worldwide after her assailants, Morgan Geyser and Anissa Weier, claimed they did it to please a fictional character named "Slender Man." Leutner, Geyser and Weier were all 12 years old at the time.
"20/20," which has followed Leutner’s case closely since her attack as well as her recovery for years, spoke with her parents exclusively in 2014. Leutner, who was still recovering after the stabbing, appeared alongside her parents on "20/20" but chose not to speak out at that time.
Now 17, Leutner has worked hard over the last five years to heal and rebuild a normal life. She told ABC News that she was ready to reclaim her story.
"I feel like it's time for people to see my side rather than everyone else's," she said.
Payton, Morgan and Anissa become friends
In 2014, Leutner was a sixth-grader in Waukesha, Wisconsin, when Geyser and Weier attacked her after a slumber party at Geyser's home. They had been celebrating Geyser's birthday the previous night.
Leutner described herself as hopeful and positive before the attack, and said she'd tried to see the good in people, including Geyser. Leutner said Geyser had struggled to make friends and that in fourth grade she'd befriended Geyser herself.
"She was sitting all by herself and I didn't think anyone should have to sit by themselves," Leutner told Muir.
While they were friends, Leutner said, Geyser seemed like a happy girl, albeit "a little lonely." They would have sleepovers together, play outside and draw -- "all the things that kids do," Leutner said.
Leutner said she'd considered Geyser her best friend and thought Geyser was somebody she could trust.
"She was funny, I will give you that," Leutner said. "She had a lot of jokes to tell. … She was great at drawing and her imagination always kept things fun."
Then, "everything went downhill," she said.
Around the time Geyser became friends with Weier in sixth grade is when Geyser also started talking to Leutner about "Slender Man," she said.
"I thought it was odd. It kind of frightened me a little bit," Leutner told Muir. "But I went along with it. I was supportive because I thought that's what she liked."
Eventually, though, the fictional stories Geyser told about "Slender Man," a tall, faceless creature in a suit that could use tendrils growing from his back, became too frightening, Leutner said. She even asked her mother, Stacie Leutner, whether "Slender Man" was real and was relieved when she was told that he wasn't.
"I told [Geyser] that it scared me and that I didn't like it," Leutner said. "But she really liked it and thought it was real."
Leutner even considered ending her friendship with Geyser, she said.
"I saw the change from fifth to sixth grade when she met Anissa," she said. "That's when I was really wanting to get out of that friendship."
Ultimately, however, Leutner stayed friends with Geyser. She said she felt bad for her friend and didn't want her to be alone. Geyser even "guilted" Leutner into staying friends, Leutner said.
"Payton was such an empathetic kid," her mother, Stacie Leutner, told ABC News in a new interview. "She recognized that Morgan maybe wasn't the healthiest friendship to have. But if Payton wasn't her friend, she wouldn't have any other friends. So, she thought everyone deserved at least one friend."
As Geyser's fixation with "Slender Man" grew, it appeared to Leutner that Geyser's friendship with Weier blossomed, too. Weier lived in the same apartment complex as Geyser and rode the bus with her to school.
"I didn't like [Weier] at all," Leutner said. "I just hung out with her because I knew that Morgan really loved her as a friend. But she was always cruel to me. I feel like she was jealous that Morgan was friends with me and her."
It was Weier who had "really convinced" Geyser that "Slender Man" was real, Leutner thought. Leutner said she is now convinced that Geyser and Weier were a toxic combination.
Morgan Geyser has her 12th birthday party
Leutner said she had no idea what the two girls had planned for her in the name of "Slender Man" when she arrived to Geyser's 12th birthday party. The trio had skated together at a local roller rink and eaten frozen yogurt before the slumber party. Looking back, Leutner said she thinks she can recognize a glimpse of something feeling off that night.
"Something was strange because at all of our past sleepovers, [Geyser] always wanted to stay up all night because she could never do that at home," Leutner said of Geyser. "But on [the night of] the birthday party, she wanted to go to bed."
"Once I look back on it, I was like, that is really weird," she told Muir. "Why didn't I see something? Why didn't I notice something was weird? But I'm not blaming myself at all. Because who could ever see something like this coming? Nobody could ever see something like this coming."
Geyser and Weier later told investigators that they had planned to kill Leutner in her sleep that night, according to their police interviews, but then they changed the plan to kill her the next morning at a nearby park.
"I remember waking up," Leutner said. "They had already gone, woken up and gone downstairs on the computer. So I woke up and I went down with them. We had doughnuts [and] went to the park."
Leutner said that it was Geyser's idea in the morning to go to the park and that normally Geyser wouldn't have been allowed to go without an adult. But because she was with friends and it was her birthday party, her mother had let the three girls go on their own, Leutner said.
Once the girls got to the park, the plan to kill Leutner changed again. Weier told investigators that she suggested they go for a walk to play hide-and-seek in nearby woods
"They just wanted to go on a walk," Leutner said. "And I didn't think much of it. It's just a walk. It's in Waukesha. What bad stuff happens in Waukesha, Wisconsin?"
In the woods, as they prepared to start what Leutner thought would be a game of hide-and-seek, Weier told Leutner to lay down.
"Anissa told me to lie on the ground and cover myself in sticks and leaves and stuff to hide, in a sense," Leutner told Muir. "But it was really just a trick to get me down there."
With a kitchen knife Weier told investigators Geyser had brought from her home, Geyser repeatedly stabbed Leutner.
Leutner said she didn't remember every detail of her brutal attack and was glad for the relief in not knowing. But, she said, she does remember her trust being broken by her best friend and not believing that Geyser and Weier were going to get help for her.
After Geyser stabbed Leutner with the knife, she and Weier left Leutner alone in the woods. Injured and bleeding, Leutner did what many couldn't believe she had the strength to do: She pulled herself out of the woods and into the open where someone could find her.
"I got up, grabbed a couple trees for support, I think," she said. "And then just walked until I hit a patch of grass where I could lay down."
It was there, at the end of Big Bend Road, that a bicyclist found her and called 911. Police and EMT workers arrived. Leutner's focus, she said, faded in and out while in the ambulance.
"I couldn't focus much because my body was working so hard to keep itself alive," she said. "It was probably like, 'Vision isn't really a priority right now.'"
Payton Leutner undergoes surgery in the hospital
At the hospital, she told Muir, she remembers seeing her mother as nurses counted her wounds.
"I said, 'You're gonna be OK. It's gonna be fine,' but I could see that she was covered. Her arms and her legs and her abdomen, they were covered in stab wounds," Stacie Leutner told ABC News in 2014.
The doctors at ProHealth Waukesha Memorial Hospital performed emergency surgery and were shocked by Leutner's critical injuries. The stab wounds she'd suffered to her arms and legs had only damaged soft tissue, but the two to her torso had hit major organs. One had cut through her diaphragm, damaging her liver and stomach. The other had nearly penetrated her heart and missed a major artery by less than a millimeter.
"If the knife had gone the width of a human hair further, she wouldn't have lived," Dr. John Kelemen, who operated on Leutner that day, told ABC News in 2014.
When she awakened after six hours of surgery, Leutner said, she first started worrying about where her attackers were.
"I remember the first thing that I thought after I woke up was like, 'Did they get them?'" she said. "'Are they there? Are they in custody? Are they still out?'"
She said she was relieved to hear that police had captured both Geyser and Weier as she struggled with the pain from the attack and surgery.
"I wrote on whiteboards to communicate because I couldn't speak much," Leutner said. "I had the intubation tube in my lungs because I couldn't breathe on my own for a while."
Her recovery was difficult, both physically and emotionally. She said she was also frightened after the attack and slept in the bed with her mother so she wouldn't be alone at night.
To this day, Leutner told Muir, she sleeps with a pair of broken scissors under the pillow next to her "just in case."
When Leutner learned why Geyser had stabbed her, she said, she wasn't surprised by the motive: The girls had intended to kill her to appease the fictional character "Slender Man" and prove that he was real.
"After I heard why she did it, I was like, 'Well, this doesn't surprise me at all because she believed so hard in this thing that she would do anything for it.'"
What did surprise Leutner, she told Muir, was that Geyser and Weier had immediately confessed to the attack and that they'd told police they had been planning it for a long time.
"It was a little shocking to me to see that they had this big, huge plan that they had been working on for months," Leutner said.
Payton Leutner regains a sense of normalcy in her life
Since the attack, Leutner said she has done her best to resume a normal life despite the notoriety of the case and the years of litigation. Trusting others, especially new friends, she said, has been particularly difficult after the attack.
"She has friends, but initially, even with those friends, she kept them at arm's length," Stacie Leutner said. "And for a long time, even trusting family members was hard for her."
Payton Leutner told Muir that she sometimes thinks about her former best friend's mother, Angie Geyser, with sympathy.
"I've thought about what she's going through and how hard it must be for her," Leutner said. "Because I'm sure a lot of people are trashing on her and hating her. And saying that it was her fault, she raised [Geyser] wrong."
"It wasn't [Angie's] fault," Leutner continued. "Morgan's schizophrenic. There is nothing that she could have done to stop that or control that. It was not her fault."
In 2016, Geyser's mother told a newspaper that her daughter had been diagnosed with early onset schizophrenia while in custody. A forensic psychologist also testified for the defense during a 2015 hearing that Geyser's father had been hospitalized several times as a teenager because of mental illness, according to that newspaper.
Stacie Leutner also said she has thought about the mother and father on the other side of the shattered friendship.
"I was angry for a long time, especially [at] Morgan's parents, knowing that Morgan's dad had schizophrenia. ... For a long time I thought that they were maybe just in denial and ignoring her symptoms," Stacie Leutner said. "But I'm not angry anymore, because I recognize that they're going through their own hell."
Geyser and Weier were charged in adult court with first-degree attempted intentional homicide after the attack.
Weier pleaded guilty to a lesser charge and was found by a jury to be not guilty by mental disease or defect in 2017. Geyser pleaded guilty to the first-degree charges against her. In 2018, as a part of her plea agreement with prosecutors, Geyser was convicted but found not guilty by reason of mental disease or defect.
Weier and Geyser each were sentenced to up to 25 years and up to 40 years, respectively, in a mental health institution.
Leutner said she is aware of the longstanding public debate about whether the two girls were old enough to be charged in adult court, but doesn't herself question whether their cases should have been handled in juvenile court.
"Adult crime is adult court," Leutner said. "If they had stolen a candy bar, sure that's a child. But you tried to kill somebody. That's an adult crime."
Leutner said she doesn't ever want to see or talk to Geyser or Weier again, and said what Geyser did was "probably unforgivable." She knows Geyser is already eligible to petition the court for release from the mental institution, but said she doesn't fear her eventual release.
"If she ever like tried to come by me, she would go right back where she was," Leutner said.
Stacie Leutner acknowledged her own reservations about Geyser potentially petitioning for release soon.
"I don't know that I'm comfortable with her being released right now," Stacie Leutner said. "I know that their sentences were up to 25 and 40 years, and if that's how long it takes, then that's how long it takes."
Payton Leutner on what she would tell her former best friend who attacked her
Payton Leutner even surprised herself when responding to the question of what she would like Geyser to know, she said.
"I would probably, initially thank her," Leutner said to Muir. "I would say, 'Just because of what she did, I have the life I have now. I really, really like it and I have a plan. I didn't have a plan when I was 12, and now I do because of everything that I went through.'"
"I wouldn't think that someone who went through what I did would ever say that," Leutner said. "But that's truly how I feel. Without the whole situation, I wouldn't be who I am."
Leutner is a senior in high school and plans to attend college in fall 2020. She said she'd like to pursue a career in the medical field, which she believes is a goal inspired by what happened to her.
To the many people who supported Leutner and sent her well-wishes through the years, she said she is "very grateful for all of the love and support." She said she now wants people to know that she is doing well and that her hope for moving forward is to "put everything behind me and live my life normally."
"We've seen her go from a victim to a survivor," said Leutner family spokesman Steve Lyons of SJL Government Affairs and Communications. "Now she's a young lady with a really bright future ... [She has] great grades, great friends. She's got so much to live for and I can't wait to see what the next chapter of her life is."
As far as "Slender Man" goes, Leutner said she had advice for parents whose children might not understand the difference between what is real and fake online.
"Parents need to talk to their kids directly, saying, 'This is not real. This is fake,'" she said to Muir.
She also shared some sage advice to young people regarding bad friendships that she wished she'd known at 12 years old.
"Get out before something bad happens to you," Leutner said. "Even if you're guilted into it, if you've been friends with them for years. … If you feel something is bad, you need to get out while you still can."