Who is Alice Vonnegut from Slapstick: Or, Lonesome No More! and what is their importance?

Alice Vonnegut is Kurt's older sister. She is mentioned in the prologue, where the author explains how his relationship with his sister impacted ideas in the novel. Eliza was in part modeled after her. Alice Vonnegut died of cancer two days after her husband died in an accident. They left four young boys, three of which Vonnegut and his wife adopted and raised.