Reckless Series by Cornelia Funke

Jacob Reckless has only a few months left to live. He's tried everything to shake the Fairy curse that traded his life for his brother's — legends such as the All-Healing Apple, the Well of Eternal Youth, the blood of a northern Djinn. And yet hope after hope is extinguished. After months of fruitless searching, Jacob journeys through his father's mirror one final time to deliver the bad news to Fox... moreJacob Reckless has only a few months left to live. He's tried everything to shake the Fairy curse that traded his life for his brother's — legends such as the All-Healing Apple, the Well of Eternal Youth, the blood of a northern Djinn. And yet hope after hope is extinguished. After months of fruitless searching, Jacob journeys through his father's mirror one final time to deliver the bad news to Fox. There they hear of one last possibility — an item so legendary that not even Mirrorworlders believe it exists: a crossbow that can kill thousands, or heal one, when shot through the heart. But a Goyl treasure hunter is also searching for the prized crossbow. Jacob must find it first — and somehow persuade Fox to do whatever it takes to save him. less

Jacob Reckless continues to travel the portal in his father's abandoned study. His name has continued to be famous on the other side of the mirror, as a finder of enchanted items and buried secrets. His family and friends, from his brother, Will to the shape-shifting vixen, Fox, are on a collision course as the two worlds become connected... moreJacob Reckless continues to travel the portal in his father's abandoned study. His name has continued to be famous on the other side of the mirror, as a finder of enchanted items and buried secrets. His family and friends, from his brother, Will to the shape-shifting vixen, Fox, are on a collision course as the two worlds become connected. Who is driving these two worlds together and why is he always a step ahead? This new force isn’t limiting its influence to just Jacob’s efforts – it has broadened the horizon within MirrorWorld. Jacob, Will and Fox travel east and into the Russian folklore, to the land of the Baba Yaga, pursued by a new type of being that knows our world all to well. less