There's no denying that Kristina and her big sister have always had a close relationship. As the other child from their mother's first marriage, Kristina has particularly attachment to Leigh because, for a long time, Leigh and her mom were all she had. "She, Leigh, and I were the trinity," Kristina tells us. "We baked together. Canned together. Planned together" (The Kitchen Was Warm.4-5). Now, though, Leigh is more than just an older sibling—she's a reminder that this close relationship all but evaporated with the entrance of Scott and Jake into their lives.
Leigh is a college student caught up in a period of sexual exploration. She identifies as a lesbian and while her parents love her, they don't exactly love this decision. "When she outed, I cringed," Kristina says. "Mom cried. [Dad] called her queer" (I Got in a Car with a Stranger.2). She openly speaks to Kristina about her girlfriend, Heather, and is responsible for Kristina developing some empathy for other people, like her classmate Trent Rosselli, who struggle with being accepted due to their sexual orientations.
More than that, though, Leigh is one of the few people Kristina can trust with just about anything, including her homemade tattoo from Adam, which Leigh discovers when she walks in on Kristina in the shower. "I'd never told her secrets," Kristina says, "and trusted completely she would never betray mine" (Leigh Knew.2-3). She's right, too—Leigh does some amateur nursing on the tattoo to get the swelling down and even gives Kristina a cycle of antibiotics she never finished. When Mom does find out about the tattoo, it's because of a loose bandage, not Leigh's loose lips.