It resonated with him during training, and compelled him to stick with it.
Not everybody the school invited to MVP followed through. It takes a lot for teens to reject a lifetime of cultural programming, to suddenly tell teammates what's not OK, or to call the cops on friends when a party gets out of hand.
But several who stuck with it described a catharsis or awakening.
"We've learned the power of sharing lessons and talking to your peers," Sexton said. "It's our role to talk about these issues and share them with others."
On a cold, rainy evening in April, about a month after Nate was sentenced, the MVP team gathered in a classroom to run through some of those lessons.
As they rolled in after sports practices and games, they were an unmistakably athletic crowd -- confident expressions, strong builds, a wardrobe of sweats, Under Armor and Lincoln-Sudbury Warriors varsity jackets.
The group planned to perform at a school assembly where they would demonstrate healthy relationships and bystander intervention. But this time, they wouldn't use made-up stories or examples.
Instead, they'd use details from the Steubenville rape case, and from Lauren and Nate's relationship.
"We want to focus on what was overlooked and how people could have responded differently," Chen explained as the students took their seats.
Students followed along on their phones as Chen went through the presentation slides, beginning with pictures of Lauren and Nate.
"Just looking through these pictures shows that Lauren and Nathaniel were normal high-schoolers, in what seemed to be a healthy relationship," Chen read aloud. "They went to prom, participated in normal extracurriculars, and they were looking forward to an exciting four years in college. They had a bright future, just like all of us here. But something went wrong, and their relationship became abusive.
"So what happened? What is abuse? What are the warning signs, and how can we, as high school students, ensure that such a tragedy never happens again?"
Chen read aloud, defining dating abuse -- any behavior that one person uses in a relationship to gain and maintain control over their partner -- and the forms it comes in: verbal, physical, emotional-psychological and sexual.
He showed another slide that said, "Maybe they could've taken action." It included a photo of Lauren and her friends, arms locked.
Chen looked around the room for feedback
"It's risky to directly tie Lauren's friends to the warning like that. It might sound like we're saying they didn't do enough," one student volunteered.
Together, they decided to swap the picture for a shot of Lincoln-Sudbury students and to make the language pronoun neutral.
It's a question the students struggle with, and a criticism the bystander theory faces: How can anyone tell when it's appropriate or safe to get in someone else's business? Where's the line between an overreaction and preventing a murder?
Learning the warning signs becomes important, Lincoln-Sudbury senior Paul Sorbo said, so people have "the critical thinking skills necessary to make those calls."
"We're fighting the underlying causes of what allowed that situation to get as extreme as it did. By getting this sort of training, you start picking up on things that fall into the gray area."
Heeding warning signs
Lauren and Nate were together throughout most of high school, a picture-perfect couple from the moment they started dating freshman year. He was a tall and handsome football player who impressed her father with his grace and humility on the field. She was nearly a foot shorter, with piercing green eyes -- the popular girl who was nice to everyone and seemed to excel in everything she tried. She was the captain of the tennis team who won the lead role in a local theater production of the musical "Annie" without any theater training.
But trouble stirred beneath the surface. None of Lauren's friends liked her boyfriend, said Lauren's mother, Mary Dunne. He was jealous and prone to violent outbursts, like when he hit a boy she danced with and kissed at a 2009 party, when they were on a "break." He once broke a windshield and punched holes in his family's living room wall, Dunne said, although the jury in his trial never heard that. Such evidence would be more prejudicial than probative, Judge Peter Lauriat ruled, given how much time passed between them and Lauren's death.
Malcolm Astley, Lauren's father, said it would be easy to dismiss Nate as a "monster." Instead, the retired high school principal is trying to learn from his daughter's death and find ways to prevent more tragedies. As a father and educator, it helps him cope.
Nearly two years after her death, evidence of the petite, fair-skinned teen remains strewn throughout the home; a pair of black high heels rests among her father's shoes near the door; framed class portraits and pictures with friends adorn walls and tables.