From the moment they meet, Allysa serves as not just a coworker to Lily, but a friend and confidante. Their first encounter demonstrates Allysa’s strong, forthright, and self-assured personality, as she walks straight into the flower shop and offers to help Lily with anything she needs—cleaning, decorating, design. Lily notes that Allysa is well-dressed, her smile genuine. Allysa says from the outset that she doesn’t need a job—she even offers to work for free, a suggestion Lily rejects. We later learn her husband Marshall sold some apps he developed and became very wealthy, and that part of Allysa’s motivation for working with Lily is her need for a distraction from her struggles with fertility.
Allysa’s friendship with Lily brings Ryle into her orbit. That Allysa is related to Ryle makes Lily’s relationship with him more complicated; Ryle is not just her boyfriend and later husband, but her best friend’s brother. As someone who knows him better and has known him for longer, Allysa offers Lily insight into Ryle’s character she would not have received otherwise—she tells Lily that Ryle doesn’t have “the best track record when it comes to relationships," foreshadowing his anger issues, and mentions he’s never met a girl’s mother before, making it clear to both Lily and the reader that Ryle, in spite of any mixed signals or doubts, is serious about Lily. Lily is perturbed that Allysa doesn’t initially seem excited about her and Ryle dating, but brushes it off. Allysa later insists, after she learns about Ryle's abuse, that he tell Lily about Emerson, the brother he accidentally killed when they were children. This revelation complicates Lily’s feelings about the situation. When Lily finally confides in Allysa about her pregnancy and Ryle’s continued abuse, she expects Allysa to tell her to take his past into consideration as she did the first time and find a way to forgive her brother, but Allysa surprises Lily by telling her if she doesn’t leave him, she’ll never speak to her again, highlighting the strength of their bond and removing any and all doubt about Lily’s decision.