The unborn evil twin one is called "The Perfume" and the alive girl is Dove and the evil twin's name is Wing and she's secretly Egyptian, I believe.

This post and the comments thereon are making me uncomfortably aware of how much of my brain space is apparently dedicated to the plot details of Caroline B. Cooney books.

YES. The girl with the tri-colored hair is in a trilogy of books called Fog, Snow, and Fire, and the evil twins book is called Twins, and the amnesia-but-not-really one is called Unforgettable, and I've read so many Caroline B. Cooney books and now that Mallory has posted about her we can all finally talk about it!

Maybe "The Stranger"? He fell into a cave and died there and then the cave was sentient so he reassembled himself like Swamp Thing but with a hot-boy glamour over top of it, and went to high school and a girl got a crush on him, but he couldn't ever really leave the cave because his dead rotting corpse was still in there?

The best thing about that one is that it started out with a bunch of drama surrounding the Madrigals Club, and you thought it was going to be about Madrigals, but it was just about how the girl got kicked out of Madrigals because there was a better soprano at their school now and so she had to take a dumb art class instead and that's where she met Jethro the Hot Undead Cave Corpse.

Caroline Cooney is the greatest, is what I'm saying.

Jodie had the WEIRDEST mood swings around Janie. Like remember the scene where they're all hanging out playing Nintendo and bonding and having a great time and then Stephen brings out chocolate chip cookies and Janie hesitates to take one because she's having a weird missing-her-parents moment and has tensed up again and Jodie THROWS THE PLATE OF COOKIES ACROSS THE ROOM AND SCREAMS AT HER. Like, I get that you're a teenage girl, Jodie, but Janie didn't even SAY anything, she just got a weird look on her face, and every single adult in your life and also every single one of your teen girl friends has attempted to explain to you that Janie is having a traumatic experience and is effectively bereaved and having an identity crisis at the same time, so maybe try to chill the fuck out for one second when she gets a look on her face that isn't "oh the joy of belonging to this new random family I never heard of"?

Stephen too, but mostly Jodie. Every time Janie said the slightest thing about pizza or horseback riding lessons Jodie would be like "I HOPE YOU DIE IN A FIRE, YOU SPOILED BRAT" and then when Janie went back to Frank and Miranda Jodie was like "WHY?" Gee, Jodie, I can't imagine, why wouldn't anyone want to share a room with you?

Just that the heroine spends most of the book tharn.