The Legendarium's Darkest Tale (Harry Potter & Winx Club Fanfic)

When the Winx find a dementor on the Island of Tir Nan Og, they are definitely terrified. They manage to defeat the dementor with the help of their Mythix wands and guardians of Sirenix, they defeat it, but not before Head of Auror office Harry Potter realises that the dementor has gone astray. Teaming up the Winx, Ha...