O livro que você está procurando é Mirror Dreams de Catherine Webb. O nome do personagem principal é Leanan Kite .
Isso é como o vice-versa que eu continuarei procurando porque o romance soa maravilhoso ( e eu meio que quero ler para mim mesmo.
Encontrei-o ao analisar a secção 'Literatura' da página dos 'territórios dos sonhos'.
Descrição de TVTropes:
Catherine Webb's Mirror Duet is primarily set in the world of dreams where people from Earth appear when they sleep, seeking their ultimate dream. Each kingdom in this world caters to different dreamer tastes: the main character controls a kingdom which specialises in storms.
Descrição da Amazon:
Every dream you've ever had, and every dream yet to come, exists in the Kingdoms of the Void. Every nightmare, too. Because there has to be balance—it's the rules. But the Lords of Nightkeep aren't big on rules—only Conquest, Fear, and Eternal Darkness for All. It takes a powerful wizard like Laenan Kite to keep them in check. But Kite has other worries, and Nightkeep is growing strong. Its Lords hunger for power. And they've turned their gaze towards earth.