Because you like Kima Greggs in The Wire

His murderous megalomania aside, Loki is quite charming. Just don't mention his strapping older brother; he's a tad jealous. See them in Marvel Cinematic Universe.

L is enigmatic, child-like, and one of the smartest people in the world. See them in Death Note.

A wildly brilliant detective, Sherlock Holmes can figure out everything except how to interact with other human beings. See them in Sherlock.