Susannah "Beck" Fisher - The rock that everyone seems to cling to. Even in death her calming force is referenced and used by all as they navigate through the different situations in their lives. She dies of cancer by book two, but is heavily remembered by her family and friends throughout the course of the remaining series. It is discovered she left letters to "the summer kids" in the final book to read on their wedding days. She is shown to be very friendly, loving and compassionate. Her death hits everyone hard and life without her seemed near impossible and takes everyone almost a year to pull themselves together and to form a life without her existence.

Mr. Fisher - A man who is known to have his way no matter what it costs or who it hurts. He is Susannah's husband and father of Conrad and Jeremiah. After she dies, he turns to whiskey. He drove Conrad away after Conrad saw how badly he began treating Susannah, such as cheating on her and running away when she got cancer. He tries to sell the summer house in It's Not Summer Without You after she dies and is barely stopped in time by Conrad and everyone else (excluding Steven who is away in college.) In the final book, he tries to mend his relationships with his sons and pays for Jeremiah and Belly's wedding despite not agreeing with them on getting married at such a young age.

Taylor Jewel - Belly's best friend despite being polar opposites. Unlike Belly, she is boy crazy and shallow, though by We'll Always Have Summer, she grows up and has something wise to say for once. In the first book of the series as seen in flashbacks, she is boy crazy and goes Steven, Conrad and Jeremiah almost at once during her first and only stay at Cousins, all in less than a week. By We'll Always Have Summer, she is shown to have grown up a bit.

Laurel Conklin - Belly and Steven's mother as well as Susannah's best friend. She is rigid and desperate to have the relationship with Belly that her daughter had with her best friend Susannah.

Steven Conklin - Belly’s brother Steven is a good friend and supportive brother.