Was Actually Friendly

"We are the angels and we live forever We're waiting for you to share our life We show you the world through our eyes Come follow us into the night"

- Blutengel, "Black Angels".

There's this group that Bob believes/suspects to be totally evil. Maybe the group has been subjected to Demonization, or maybe it simply looks really scary/suspicious to Bob. However, a little friendliness can go a long way. Maybe it doesn't take more then an outstretched hand for Bob to change his mind?

If Dark Is Not Evil, then this might be how Bob makes a Heel Face Turn as he stops being a Principles Zealot or Windmill Crusader or whatever his problem was. However, if the group really is The Dark Side (rather then merely Darker and Edgier), it might instead be how he makes a Face Heel Turn. This subversion is closly related to Affably Evil. If BOTH sides are good (at least in Bob's eyes), then this may be how Bob becomes a peacemaker between them... or get stuck in the Face Heel Revolving Door.

If the group is religious or political this social conversion might lead to Easy Evangelism, as Bob listens sincerely to whatever his new friends are saying.

On a psychological level, this phenomenon is largely the same thing as Critical Backlash. (Note however that this trope is an in-verse reaction while Critical Backlash is an audience reaction trope.)

Compare Easy Evangelism for the religious or political version - this trope works on a purely emotional level. Of course, it can still lead to Easy Evangelism, as a righteous hero or Manipulative Bastard gain Bob's trust on a personal level before he drops the anvil. Also compare Freaky Fashion, Mild Mind.

Film

 * Preaching to the Perverted runs on this trope, with the protagonist being very surprised that the people at the club he's infiltrating turns out to be really nice people.
 * In Easy A, Marianne really hated Olive. But when Olive showed her a bit of kindness and support, she quickly changed her attitude and wanted to be friends instead. It didn't last long, but that's for entirely different reasons.

Literature

 * Wood Elves in The Hobbit. They distrust the dwarves mutually (so the dwarves refuse to say why they're there, making the elves suspicious since they assumed the starving dwarves approaching their banquet to beg for food were attacking). They turn out to be a lot nicer later on, . Arguably the men of the lake as well.
 * Crosses with Fire-Forged Friends; everybody is about to kill each other until
 * The Sini Mira in The Native Star turn out to be Actually Friendly, although the main characters never discover this.

Live Action TV

 * In one episode of Star Trek: The Next Generation, a Star Fleet officer is tasked with infiltrating the Maquis, a group of outlaw Federation citizens fighting the evil Cardassian empire in clear violation of a peace treaty between The Federation and The Empire. This gets harder and harder for her as the local leader insists on being really nice to her and talking about various sentimental stuff.
 * In one episode of Star Trek: Voyager, the protagonists themselves do this to a civilization that is very powerful but also very afraid of them.
 * Stargate SG-1 episode "Forsaken". The team runs into a group of humans with a downed spaceship harassed by evil-looking Rubber Forehead Aliens. They later found out that humans were convicted criminals on the way to Penal Colony and said aliens were crew of the ship - Serrakins who once liberated criminals' homeworld of Goa'uld and settled there living in harmony with locals.
 * A lot of old old Doctor Who monsters are like this.
 * In a new Outer Limits episode, a newly-inaugurated President is taken to a bunker after an object is detected on the way to Earth. It is eventually revealed that alien ships are about to enter Earth's orbit. They send a message in, apparently, their own language, which linguists are trying to translate. Meanwhile, several of their actions are perceived as hostile by the US and, especially, by Russia. Faced with the possibility of an Alien Invasion and the threat of a nuclear exchange with Russia (who claims that anyone who doesn't fight the aliens will be seen as a collaborator), the President orders a strike on the aliens. It utterly fails due to the aliens' advanced technology. Furthermore, the aliens launch powerful missiles against Washington, D.C., and Moscow. Right before they hit, an advisor tells the President that the alien message was in English all along, just garbled due to their aquatic environment, offering friendship to humans.
 * Another episode also has an alien race arrive to Earth. This time, they're openly asking to be allowed to live on Earth by possessing dead humans. Throughout the episode, several characters get increasingly paranoid about the aliens' agenda on Earth. It is revealed, though, that the aliens have no evil agenda and are merely building a museum to their race, as all their children are 100% human.

Music

 * Several Blutengel songs run on this theme, with the cool vampires inviting the humans to hang out with them and maybe becoming immortal themselves.

Video Games

 * Dark Templar, from some character's points of view, in StarCraft.

Western Animation

 * In Legend of the Guardians, the pure ones seem really scary at first. (And it's also clear from the narrative that they actually are evil.) However, as the queen shows Kludd some kindness, he quickly "realizes" that they are the good guys.
 * The Sewer people in Futurama
 * Toy Story: Woody is initially afraid of the toys Sid operated on, but realizes they're friendly when they repair Buzz's arm.
 * The toys at Sunnyside at first seem friendly, then turn nasty, and then end up nice again. This is especially true of Big Baby, who initially seems very creepy, but in actuality is really just a...well, baby.

Real Life

 * Truth in Television far more often than not. Men or women, blacks or whites, liberals or conservatives, believers or nonbelievers; whoever the group may be that you don't belong to, once you leave your comfort zone and get to know them, you'll find that they're actually pretty decent people.
 * Unless the group's official policy says something like "We want Group X dead, and we plan to make that happen through direct action," most members are probably pretty decent people.
 * Among Darker and Edgier subcultures, such as Goths and kinky people, nervous newcomers are sometimes greeted with a reassuring "Welcome to the dark side, we have cookies".
 * In religious cults, this trope is often Turned Up to Eleven, a manipulation technique known as "love bombing". It tend to be extra effective on people who expected the cultists to be Hollywood Satanism (or even The Dark Side straight out of Star Wars).
 * Even without this technique, the trope easily comes into effect, especially on people with such minsconceptions: In reality, members of religious cults are usually quite ordinary people with unusual beliefs and an unusual social context. When a cult becomes destructive, it's because of the leaders and/or a clash between reality and the beliefs of the cult - not because the individual cult members are "bad people".