Stella is the sister of Betty and Polly Cooper. Part of one of the most respected families in Riverdale, and she used to love it there. With her, her sisters. Until Polly had gotten involved with Jason Blossom and things got messy.
Over the summer, Stella had gone to New York to learn about fashion, since it has always been her dream to become a fashion designer. When she came back, the town that she thought she knew was different. And Jason had broken her sister's heart and she had a mental breakdown and got sent with the Sisters.
One person she always had her eye on, has been Archie Andrews. But, since she knew that her sister Betty liked him too, she had stepped aside and allowed her sister to be happy while she focused on what she wanted to do. She had almost always put the needs of other people before her own. One of the reasons why she left Riverdale for the Summer was so she wouldn't be tempted to do something with Archie and ruin her relationship with Betty.
And while it was nice to get away, and she did make a new friend there named Veronica Lodge, when she came back she had found that not only did her sister like Archie, but so did her new friend.
