Iron Fey by Julie Kagawa
All Meghan ever has to worry about is the people in school making fun of her and her stepfather forgetting her existence. But it's her sixteenth birthday – now she will become a woman, won't she, she will have adventure, romance... won't she? Yes. But not as she thought. When Meghan's five-year-old brother is abducted by a creature from the faerie world. In order to save him, Meghan has to follow him to the Court of Oberon... and make a few life-changing deals, like the one with the Winter Prince Ash... Who happens to be the arch-enemy of Meghan's best friend – the Puck from A Midsummer Night's Dream...
Winter's Passage, The Iron Daughter, The Iron Queen, Summer Crossing