If you like The Key by Marianne Curley
Having liked the book, The Key by Marianne Curley, here are some other titles you might enjoy reading.
Out of Time by Caroline B. Cooney.
Annie Lockwood exists; everyone admits it. Everyone has seen her. But only Strat insists that Miss Lockwood traveled one hundred years back in time to be with them in 1895. Now Strat is paying an enormous price: His father has declared him insane and had him locked away in an asylum. When Time calls Annie back to save Strat, she does not hesitate, even though her family is falling apart and desperately needs her. Can Annie save the boy she loves, or will her choice keep her a trespasser out of time?
Singing the Dogstar Blues by Alison Goodman.
In a future Australia, the saucy eighteen-year-old daughter of a famous newscaster and a sperm donor teams up with a hermaphrodite from the planet Choria in a time travel adventure that may significantly change both of their lives.
Lirael: Daughter of the Clayr by Garth Nix.
Fourteen years after events in Sabriel, Lirael discovers a unique destiny in the depths of the Clayr’s Glacier that will pit her against a dangerous necromancer, with only a chancy magical being and the brave but reluctant Prince Sameth for assistance.
The Golden Compass by Philip Pullman.
Accompanied by her daemon, Lyra Belacqua leaves Oxford and sets out to prevent her best friend and other kidnapped children from becoming the subject of gruesome experiments in the Far North. This is Book I of Pullman's "His Dark Materials" trilogy.