- "Such a shame. Your wedding was the last thing I was living for. I lost a grandson, but you, you've lost the love of your young life. Poor child."
- —Rose to Betty (thinking she was Polly)[src]
Fairly little is known of Rose's early life. What is known, is her affection for Polly Cooper. She took a liking to Polly as the young lady dated Jason, her grandson. At some point during their relationship, Rose gifted Polly with a ring that had been in the Blossom family for generations.
Betty Cooper and Jughead Jones attended Jason's memorial, hoping to learn why he would want to escape his family. In an effort to find possible clues, the two teens crept into his bedroom, unbeknownst to either of them that Rose was in Jason's room as well. However, she mistakenly took Betty for her older sister, Polly. She grabbed Betty's hand and realized that the ring wasn't on her finger. The ring that she had given Polly was a Blossom family belonging that had been with them for generations. She says that it should be kept by Polly's heart at all times, but should Penelope find out, she'd take it from her. Still under the misconception that Betty is Polly, Rose went on to say that it's a shame that Polly and Jason never got married, their wedding was the last thing she was looking forward to. She lost a grandson, but Polly lost the love of her life. 
It was shown via flashback that Nana Rose gave Jason her blessing to marry Polly, however, as revealed in a previous episode, her blessing was not the only thing she gave Polly and Jason, she also gave them her heirloom ring. Present day; Rose attended Polly Cooper's Baby Shower following the discovery that she was pregnant with Jason's child. Upon her arrival, Nana Rose performed some kind of ritual on Polly to identify the baby's gender by using a purple stone pendulum, which led Cheryl to remark that Rose had dementia as well as "gypsy blood," offered as an explanation for her doing this. According to Nana Rose, Polly was pregnant with twins, a boy and a girl. 
Rose is an elderly woman with a frail body, pale skin, and white hair, with a red streak. Notably, Nana Rose has what appears to be some kind of eye condition, possibly blindness as her left eye is a milky-white color, while her right eye is hazel, and looks perfectly fine. Unsurprisingly, she's known to wear clothing that one would expect an elderly person to wear, such as wool sweaters and long, dark-colored skirts.
- "Chapter Five: Heart of Darkness"
- "Chapter Eight: The Outsiders"
- "Chapter Eleven: To Riverdale and Back Again" (mentioned)