Foreign Detectives

L from Death Note:

L is ruthless and dedicated.  For example, he murdered a man on public TV to advance his investigation into a serial killer.  The guy who he killed was a criminal on death row set to die that day, which was how he justified the death.

Ciel Phantomhive:

Ciel has a complex set of motivations.  He is 14 years old who is "the queen of England's watchdog," which is to say he watches over the criminal underworld and strikes only at the most opportune times when the queen commands it.   To keep watch over criminals, he acts as one.  He leads the opium trade.  The reason why he is acting in the capacity of watchdog is that his parents were murdered, his home was burned down, his innocence was taken, and his body was almost sacrificed to God by a masked cult. Before he was about to die, he sold his soul to a demon in exchange for killing the persons who committed these atrocities.  Only problem is that he first has to discover the persons behind it.  He uses his position of watchdog to unravel that mystery while executing orders for the queen and maintaining his position as a drug lord.