Friend to Psychos

For your average bloodthirsty maniac, the greatest challenge they face will be making sure Johnny Law doesn't catch up with them. They'll have to take great care covering up the evidence of their crimes and either fleeing or fighting when the cops or the Vigilante Man show up.

All this becomes a lot easier when they've got a Friend to Psychos on their side. This friend is someone who, while not a homicidal maniac themselves, helps a maniac get away with their rampages. It could be there's some sort of family connection between friend and psycho. Or maybe the maniac is a Psycho for Hire, and their employer doesn't want one of their best workers rotting in jail. Or it could just be that they think this particular psychopath is a really nice guy; they might even be in love.

Whatever the case, expect the Friend to Psychos to be responsible for throwing the police off the trail, disposing of bodies, giving the psycho a place to hide, and fighting The Hero when they come to take the psycho down.

Compare Psycho Supporter, where the friend is just as nuts as his or her boss.

Anime and Manga

 * In Descendants of Darkness there's Mibu Oriya, an old friend of Muraki. He covers up for Muraki, gives him a place to stay, and even disposes the bodies sometimes.
 * in various arcs of Higurashi no Naku Koro Ni. Friends will help you move, but only best friends will help you move bodies.

Comic Books

 * Two Sin City stories feature serial killers who get away with their crimes for so long because members of the influential Roarke family are protecting them. In That Yellow Bastard, Junior is able to get away with raping, torturing, and killing hundreds of children over a very long career because his father is Senator Roarke, a man with the entire Basin City government in his pocket. And in The Hard Goodbye, the cannibalistic Kevin has his crimes covered up by Senator Roarke's brother, the even more powerful Cardinal Roarke, who seems to believe Kevin was somehow chosen by God to eat prostitutes' souls.

Film

 * In Maniac Cop, the villain is a former good cop who was unjustly thrown in jail. After a brutal beating leaves him scarred and brain-damaged, the coroner allows him to be declared dead and escape because he was such a hero. And throughout the film, his former girlfriend helps conceal his rampage.
 * Mary Loomis, in Psycho II.
 * Irina Karamanlis from The Anthropophagus Beast aids her insane and cannibalistic brother by disposing of the bodies of his victims, and hiding evidence, though the guilt of doing this ultimately drives her to suicide.
 * The gas station attendant from The Hills Have Eyes remake sends travellers in the direction of the mutants, and in exchange receives any valuables the victims had on them. He too commits suicide out of guilt by the events of the film.

Literature

 * In Under the Dome, when Junior Rennie is driven by a brain tumor to kill two women, his father "Big Jim" Rennie helps him pin the blame on their mutual enemy Dale Barbara. It helps that Big Jim had a couple corpses of his own he needed to dispose of.

Live Action TV

 * In the Buffy the Vampire Slayer episode "Beauty & the Beasts," Debbie tries to cover for her boyfriend Pete when he starts going through a Jekyll/Hyde situation. She's not very good at it, though.
 * This forms the main plot of the third season of Dexter.
 * On an episode of The X Files Lili Taylor played a blind woman who shared a one-way Psychic Link with a serial killer and cleaned up his crime scenes after him.

Video Games

 * No matter how you play the game in the Mass Effect series; Joker will support Shepard. Prank-call the Council that oversees most of the known Universe? He thinks it's awesome.

Western Animation

 * In Batman the Animated Series, with the exception of Harley Quinn, most of the Joker's henchmen didn't seem to share in his psychosis; they largely seemed to be in it for the money, or because they were too scared of the Joker to refuse.

Web Comics

 * The Zalia family to Oasis in Sluggy Freelance, though Oasis is more of a Friendly Neighborhood Psychopath than most.
 * Roy is kind of like this to Belkar in Order of the Stick, even putting in a good word to get the psychopathic halfling out of prison. Although in his case, it's more of a case of realizing that the Heroic Sociopath is better off in his charge, where he can keep him 'pointed at the bad guys', rather then placing his bets on the idea that any prison can hold him.