Because you like Lucy Whitmore in 50 First Dates
His murderous megalomania aside, Loki is quite charming. Just don't mention his strapping older brother; he's a tad jealous. See them in Thor / The Avengers.
Billionaire playboy by day and vigilante archer by night, Oliver Queen aims to rid Starling City of crime and atone for his past mistakes. See them in Arrow.
A benevolent madman with a blue box, The Doctor is traveling through time and space to heal the wounds of the universe. See them in Doctor Who.