In what way is Holden's relationship with Phoebe similar to his relationship with Allie?

Holden's younger brother, Allie died from leukemia. Holden holds a romantic view of innocence and purity to Holden. Allie is held on a separate level than ordinary people. Allie remains untouched by Holden's cynicism and negativity. Similarly, Holden's little sister Phoebe also holds this sense of purity and innocence. She is the one bright source in Holden's life. Both Allie and Phoebe represent the innocence that Holden and most of the world had lost a long time ago.