How can I make this girl stop hating my friend and start being returning my friend's friendly outreaches? long?

Every time I see a question regarding teen girls having a little overboard 'idols' I'm thrilled - my 13 year old daughter is certainly an 'obsessor'. I think it's great you want to help Savannah, but keep it subtle and sparse. You DO NOT want to get in the middle of this. Instead, when you're hanging out with Rachel, text Savannah and laugh and see what Rachel says. If you're really comfortable, ask Rachel what gives with Savannah. Maybe Rachel is taking Savannah's friendliness the wrong way, but you being Savannah's best friend can easily set this straight. Try to set up a time when you and your best friends, and Rachel, can hang out and Savannah can show Rachel that she only wants to be friends.