Sage is Leawood High's Queen Bee. Though she starts out sweet to Megan, but she eventually shows her true colors, an arrogant, hot-tempered, snobbish girl who thinks she's better than everyone. She was best friends with Sara Manning, the once queen bee who was kicked out of Leawood High due to vandalizing the school, framing Megan.
Since Sara was expelled from Leawood High, Sage had carried a grudge against the twins. When Megan and Jenny decided to try out for the Leawood High cheerleading squad, Sage went rough on them (to get back at her for getting Sara Manning expelled out of Leawood High), after a grueling try out, Sage accepted a few girls on the squad, except the twins. She also gives classmate Stacie a hard time calling her a freak, due to Stacie's tomboyish image.
Sage is also jealous that Jack Wheeler would rather be with Megan Healy than her. She tries to gain Jack's affections but fails. The same thing happens again when new football jock, Cody Parker develops a crush on his tutor, Michelle. She is often competing with the twins for different reason. She competes with Erin for popularity and fashion and with Michelle when it comes to guys.
During junior year at LHS, Sage had an affair with Megan's boyfriend, Matt Edwards, a star quartback at Leawood's rival Oakside High, during the school wars. In the Final Year series, she was transferred to a boarding school and was written out of the series, much to the twins' delight.
- In Double Trouble: The Final Year, Megan Healy mentions Sage when she meets Oakside High cheerleader, Courtney Townsend, who shares the same similaries as Courtney. Erin says "She the new blonder version of Sage McConnell."
- In Phoebe & Sophie, Megan mentions Sage. Megan says to her niece Sophie, who faces a rivarly with her enemy, Sydney Harper, "You know, I went through the same thing with my high-school nemesis."
- Sara Manning - She was Sage's original best friend in the beginning of the series. They both judge people about their appearences. In the first book of Double Trouble, they faced competition with two new girls, twin sisters, Megan and Jenny Healy. Megan befriends with them by lying to them that her family was rich. But, Sara discovered the deception when she sees Jenny with her crush, Jack Wheeler. Sara and Sage humiliates Jenny and bullies her. Angered by what they did to her sister, Megan slaps Sara. Unknown to them, Megan switched places with Jenny to give them a taste of their medicine. Sara later vandalizes their high school to frame Megan. But she was later discovered and was expelled from school. Since then, Sage battle the twins alone.
- Sage only appeared in the Double Trouble series before she transferred to a private school in Double Trouble: The Final Year.
- Sage is just like Dori Wallace, the Healy Twins' rival and enemy from their middle school days.
- Sage shares similar traits with Sweet Valley High character, Lila Fowler and Totally Spies character, Mandy:
- Like Lila Fowler, Sage comes from a wealthy family and wears designer outfits.
- Like Mandy, she is very popular and self-centered, focusing on her appearance, accessories and boys and she rivals with Megan Healy.
- She is portrayed by Claire Holt in the book series.
- Sage is seen on the Double Trouble book covers with Megan Healy (Portrayed by Caitlin Fein).
- Sage's grade history.
- In "Parent Trap" she gets below average grades and is grounded and her credit was taken away until her grades improve.
- In "The Tutor" she gets F's and must be tutored by Jenny Healy.
- When Sage became captain of the Leawood High's cheerleading squad, she battled the Healy twins.
- Sage is afraid of spiders.
- She admitted to having feelings for Paul Porter and was jealous that he was dating Jenny Healy at that point.
- She was in a love triangle with Megan and her ex-boyfriend, Matt Edwards.
- "You have something on your face."
Marvin: "What?" Mindy: "Ugliness."