- "Mom and Dad hated that Jason and I were dating. They were thrilled when Jason dumped me. Jason's parents forced him to break up with me. Of course, they didn't approve of a Blossom boy dating a Cooper girl. But when I told him about the baby, our baby... Oh, he was so happy, Betty. We were gonna run away. Start our family in a beautiful place."
- —Polly to Betty[src]
When Polly and Betty were little, Betty was afraid of the dark. Polly would comfort her little sister, but their mother would never allow her to stay with Betty overnight, so she would turn on Betty's night light, a light she still had.
When Polly was nine, she ran away from home after a huge fight with her mother, she disappeared for hours, and the entire neighbourhood searched for her. They would later come to find out that Polly was in the attic the whole time.
She used to be in a relationship with Jason Blossom, but it didn't end well. While they were together, Jason "meant everything to Polly, but she meant nothing to him," according to Betty. Her parents were furious about their relationship and her mother refused to acknowledge her as her daughter. This drove her to a mental breakdown, and she had to move to a group home. Her parents blamed Jason for this, but Betty blamed their mother.
Polly was also a member of the River Vixens before she was put into the group home.
When Betty helped Veronica take revenge on Chuck Clayton, they found the playbook that he and his football team members would rate their 'conquests'. In the book Polly was listed next to Jason's name, her worth being a total of nine points. Only further proving how little Polly meant to Jason, in Betty's perspective. 
While investigating Jason's murder, Betty learned of Jason's involvement in dealing drugs from Trev Brown, a former teammate of his, and went to her father and asked about Polly. Hal explained that Polly and Jason had had a fight, he was unsure what the fight was about, but Polly was left devastated as a result. Hal alleged that Polly subsequently attempted to commit suicide, and that was the real reason she was sent away, to prevent it from happening again. 
After months of being separated, Polly received an unexpected visit from Betty at the Sisters of Quiet Mercy group-home. She hugged Betty, who almost instantly noticed that she was pregnant with Jason's child. Polly had her suspicions as to why Betty never came sooner, her parents had likely been telling Betty that she was on drugs or alcohol, however, they actually told Betty that she was sick, to the point where she tried to commit suicide, and in return, they told Polly that Betty didn't want to see her, which she already knew was a lie. Hal and Alice hated that she and Jason were dating, they were thrilled when Polly and Jason broke up, but, according to Polly, that was due to Jason's parents forcing him to.
He was ecstatic upon learning that Polly was pregnant and they'd planned to run away and start a new life together. On July 4th, Polly had packed her bags, intent on meeting Jason on the other side of Sweetwater River, however, her parents caught wind of her plan to run away, and in response, they had her sent to the group home. She then asked if Betty had talked to Jason and if Betty relay a message, at that moment it was clear that Polly had no idea about Jason's murder. She had planned to go to the highway off route 40, where they'd stashed a car, take it, and meet Jason, so they could pick back up where they left off, unfortunately, Betty was forced to tell her the truth about Jason's untimely demise. Not long after, she ran into her mother in the halls of Quiet Mercy, she confronted her on the lies she told regarding Jason, while two orderlies pulled her away, but not before Betty promised Polly that's she'd get her out. As promised, Betty returned, but by then, Polly had already escaped through the broken window in her room, leaving only blood behind.
Polly appeared in a dream sequence of Jughead's, which would best be described as some kind of idealized, make-believe version of the American dream. She and Jason sat across the table, from Jughead and Betty as they held hands, her mother and father were there as well, they appeared to be one big happy family. Following her escape from the Sisters of Quiet Mercy group home, Polly hid in the attic of her house until it was safe. After a hunch led on by a discussion she previously had with Jughead, Betty found her. She told Betty that she couldn't stay at the group home, waiting for Jason when he was never going to show, they initially had a plan to move to a farm upstate, and raise the baby, Polly still wished to go there, but she didn't have the money to make it.
She couldn't stay at the house, as their mother and father wanted her to give up the baby, which Polly refused to do, and she won't have her child raised in a place that it's not wanted. Before leaving, Betty asked that Polly give her a few days to find her a safe place in Riverdale, as she doesn't want to lose her sister again. Following a meeting that Betty had with the Blossom, in which they promised to take care of Polly and her child, she agreed to meet them at Pop's Chock'lit Shoppe, where she waited. However, only Cheryl showed up, she came to warn them that her family had no intentions on protecting Polly, in fact, they wanted her out the picture. With no place to go, Veronica and Hermione insisted that she stay with them.
According Polly, who told her story to Betty, Veronica, Hermione and Sheriff Keller, what started out as a casual conversation between her and Jason, flourished into an epic-forbidden romance. But for reasons that were still unclear, their family's tried to tear them apart, however, the break up was short lived as Polly soon discovered she was pregnant with Jason's child. They subsequently became secretly engaged with Nana Rose's blessing and her heirloom ring. She and Jason had made plans to runaway in an effort to start a new life together, the last time she saw him was at Pop's Chock'lit Shoppe, where he told her about his plan to fake his own death, and meet up on the other side of Sweetwater River. Unfortunately, before that could happen, Polly was taken away to the Sisters of Quiet Mercy.
However, before they could even consider leaving town together, they needed money, which resulted in a one time drug deal between Jason and the Southside Serpents. He received an upstate address where he would deliver the drugs in exchange for cash but neither Jason nor the drugs made it that far as he was murdered and the drugs went up in flames, in his car on route 40, along with everything Polly had with him, including the heirloom ring. A couple days later, Polly was approached by Betty and Veronica with the idea that they'd throw her a Baby Shower. Initially hesitant, Polly agreed, stating that she wanted her mother there, as well as the Blossoms. The shower would be the perfect opportunity to prove to them that she wasn't an unfit mother, despite their claims that she was.
While her mother had been invited to the shower, it was clear that the chances of her actually attending the event were slim, which left Polly disappointed as Betty attempted to cheer her up. At that moment, Polly announced that she wanted Betty to be her child's godmother, if anything ever happened to her, Betty was the only one she'd trust to raise her child. That night, as the Baby Shower commenced, Polly reunited with several friends that she hadn't seen in months, such as Valerie Brown and Melody Valentine. Much to her surprise, Alice decided to attend the shower, they hugged after Alice expressed how happy she was that Polly and the baby were safe. Just then, the Blossoms arrived, Cheryl, Penelope and Nana Rose; they gifted Polly with an expensive stroller, and in return, Cheryl wanted to be named the child's godmother, unaware that Polly had earlier named Betty the godmother.
Halfway through the shower, Nana Blossom performed some kind of ritual, in which she hovered a purple stoned necklace over Polly's hand, which she claimed could read the baby's aura and predict it's gender, and according to her, Polly was having twins, one of each. The gift opening portion of the night had come, and Polly opened her mother's gift to find the old night light that she used as a child. Alice saved it, she knew how much Polly loved it, and how much it made her feel safe, so she wanted Polly's child to have it. Following the night light, Penelope insisted that Polly open her gift next, which happened to be a miniature rocking horse that belonged to great-grandfather Blossom. Polly then received an invitation from Penelope and Cheryl to live with them at Thornhill, which didn't go over well with Alice, this subsequently led to a brief argument between Alice and Penelope.
Polly jumped to her feet, yelling "enough", as she was sick of their incessant bickering, it was their pointless hate and rivalry that eventually led to Jason's death, Polly claimed. They were suppose to be together, but neither Alice nor Penelope would allow them to share that joy of being in a relationship, which costed Jason his life. After the shower, Alice apologized for her outburst, but that wasn't enough for Polly as she was still frustrated with her mother for sending away, because had she not done that, Polly would have met up with Jason, and he could still be alive. Polly explained that she was alone at the Sisters, but that was never Alice's intent, she then pleaded with Polly to return home, and if she did, her father would just have to accept that. But Polly questioned if he'd attempt to make another appointment for her.
Unbeknownst to Alice, Hal made an appointment for Polly before they sent her away, he said that he's be more than willing to pay to fix her problem, as she shouldn't have to live with her mistake. The next morning, at the Pembrooke, Betty informed Polly their mother had kicked their father out the house. Despite being free to return home with her family, Polly opted to live with the Blossoms at Thornhill, she explained that she was doing it for her child.
After moving in with the Blossoms, Polly began to ignore Betty's calls and emails, cutting off all ties to her sister. Polly was in attendance at the Blossom family's ceremonial Maple Tree tapping, where Archie confronted Polly about her failure to communicate with her family. She told him that Betty had nothing to worry about. Later that week, during a banquet at the Belmont Lodge with the entire Blossom family and board of trustees, Polly interrupted Cliff's conversation with Archie to ask him to dance. During their dance, Polly revealed that she only chose to live with the Blossoms because she suspected that they were involved in Jason's death, and needed evidence to prove it.
She ignored Betty in order to make the charade more convincing, and that's why she needed Betty to stop trying to contact her. Before heading off to bed that night, Polly stopped by Cheryl's room to say goodnight, unaware that Cheryl would go on to scratch her face out of the photo that was taken at the Maple Tree tapping. 
Polly is a very attractive teenage girl, with a slim figure, pale skin, blonde hair, and green eyes. Before she became pregnant with Jason Blossom's child and was taken away by the Sisters of Quiet Mercy, Polly was a member of the River Vixens cheerleading squad, meaning she would have likely been required to have a physically fit physique. Currently, she has grown in size due to carrying her and Jason's unborn child. As for her choice in style, despite Alice saying that Polly grew up too fast, her choice in clothing does no reflect that statement. It may be due to her pregnancy, but Polly rarely shows skin, often wearing clothes that cover her completely, such as denim jeans, and a jacket or a long colorful dress.
- "Chapter One: The River's Edge" (mentioned)
- "Chapter Two: A Touch of Evil" (mentioned)
- "Chapter Three: Body Double" (mentioned)
- "Chapter Four: The Last Picture Show" (mentioned)
- "Chapter Five: Heart of Darkness" (stock footage)
- "Chapter Six: Faster, Pussycats! Kill! Kill!"
- "Chapter Seven: In a Lonely Place"
- "Chapter Eight: The Outsiders"
- "Chapter Nine: La Grande Illusion"
- "Chapter Ten: The Lost Weekend" (mentioned)
- See also: Category:Images of Polly Cooper
- ↑ Aguirre-Sacasa, Roberto (writer) & Krieger, Lee Toland (director) (January 26, 2017). "Chapter One: The River's Edge". Riverdale. Season 1. Episode 1. The CW.
- ↑ Lawrence, Yolonda E. (writer) & Krieger, Lee Toland (director) (February 9, 2017). "Chapter Three: Body Double". Riverdale. Season 1. Episode 3. The CW.
- ↑ Maxwell, Ross (writer) & Warn, Jesse (director) (February 23, 2017). "Chapter Five: Heart of Darkness". Riverdale. Season 1. Episode 5. The CW.
- ↑ Williams, Tessa Leigh & Zwart, Nicholas (writers) & Adelson, Steve (director) (March 2, 2017). "Chapter Six: Faster, Pussycats! Kill! Kill!". Riverdale. Season 1. Episode 6. The CW.
- ↑ Allen, Aaron (writer) & Anders, Allison (director) (March 9, 2017). "Chapter Seven: In a Lonely Place". Riverdale. Season 1. Episode 7. The CW.
- ↑ Cohen, Julia (writer) & Katzenberg, David (director) (March 30, 2017). "Chapter Eight: The Outsiders". Riverdale. Season 1. Episode 8. The CW.
- ↑ DeWille, James (writer) & Rose, Lee (director) (April 6, 2017). "Chapter Nine: La Grande Illusion". Riverdale. Season 1. Episode 9. The CW.