So, The Hero's girl is pretty cute. Only it turns out the Hero isn't the only one who thinks so. She's caught the villain's eye as well. If this crush takes a turn for the perverse, this can lead to tropes like I Have You Now, My Pretty, Forceful Kiss, Bathe Her and Bring Her to Me, And Now You Must Marry Me, Scarpia Ultimatum, and Go-Go Enslavement, although none of those require a Villainous Crush. Additionally, the villain may become a Stalker with a Crush. If the crush itself is a motivating factor in his Start of Darkness, then it's Love Makes You Evil.