Everybody knows that the best relationships are the ones fraught with drama. While kind, loving relationships are all well and good, they don't make for great entertainment. If you really want to get people interested and play their heartstrings like a fiddle, you need to set up a fantastic friendship and then pull it apart. Give people a reason to care before you introduce a conflict, and you'll hook them to an amazing extent.

In the world of 'X-Men' movies and comic books, the rocky relationship between Professor Charles Xavier and Magneto is the centerpiece of the mutant soap opera. One-time friends and battle allies, their difference of opinion on non-powered humans drove a permanent wedge between them. Sure it may be tragic, but the fight scenes look impressive on the big screen. Fans are eagerly awaiting the release of June's 'X-Men: First Class,' (in theaters June 3) which examines how Xavier and Magneto met and what exactly led to their complicated love-hate relationship.

With that in mind, here's a look at five more of the best friends-turned-enemies in comics.

5. Punisher and Microchip

Frank Castle, alias the Punisher, is waging a one-man war on crime. Of course, a normal human being who decides to go around battling "crime" alone tends to get beaten up, kidnapped or killed. Frank Castle, incredibly talented though he is, is no different. Past a certain point, he needs help. At one point, this help came in the form of Microchip, a rotund hacker who lost his son to violence. Microchip hacked into security systems, procured weapons, bought safehouses, and outfitted vans with all the guns Castle could handle.

Their relationship was great, until Microchip lost his nerve. He couldn't take the killing any more and quit. That's fine -- everyone breaks. Micro's mistake was coming back years later in an attempt to recruit Castle to do some work for the CIA. More specifically, to do some work for a less than legal section of the CIA. Castle would have all the guns and targets he wanted, but he would be subordinate to the same men and women who had spent decades funneling drugs and guns all around the world. As you can imagine, this encounter didn't end well for Microchip.

4. Clark Kent and Lex Luthor

Depending on who you ask and what you're reading, Clark and Lex were best friends, acquaintances, or strangers as kids. In one of the best Superman stories, 'Superman: Birthright,' however, they were good friends who had a major falling out. In Smallville, Clark Kent was a bright and fairly popular boy. He played sports and he had friends, but he still felt a little estranged from his classmates. He found a kindred spirit in a young Lex Luthor, who was entirely too smart, and entirely too anti-social, for his own good. Despite their differences, they became tentative friends, and then good friends.

Nothing good lasts, and their relationship soon turned sour. After an experiment went wrong and Luthor misinterpreted something Clark said, the young genius left town and wiped away any trace that he'd been there. He grew up and became a billionaire industrialist, and once Superman appeared on the scene, he became the world's foremost supervillain, too. Why? Because no man can be better than Luthor, and Superman is clearly a threat to human ingenuity.

Curiously, Luthor's reason for hating Superboy a few decades back was much more absurd. When an experiment started a fire in Luthor's lab, Superboy blew it out using his super-breath. Somehow, this resulted in Luthor losing his luscious mane of red hair, causing Luthor to swear vengeance on Superboy.

3. Batman/Two-Face/James Gordon

It makes sense, doesn't it? Batman teams up with hero cop James Gordon and successful District Attorney Harvey Dent to form a three-headed crime-fighting monster. While it's of questionable legality (correction: it's totally illegal), it's easy to see why this trio was so effective. They're all aspects of the same idea. Batman represents vigilante justice, Gordon pursues justice, and Dent uses the law to ensure that justice is done.

After a mobster threw a vial of acid in Dent's face during a trial, the team-up went south in a major way. Dent's mind crumpled under the strain, and his new persona enjoyed justice, but in a different way. Two-Face thought of justice as being truly blind, and used a scarred two-headed coin to decide what was fair. If it landed scarred side up, then evil acts were coming. Clean side up? Then he would see that justice be done. This, of course, led to endless battles with Batman.
2. Thor and Loki

In terms of failed relationships, the mother lode is parent/child. A close second, though, is fraternal. Thor and Loki grew up as brothers, with all of the love and bickering that that entails. They came of age together, battled goblins and monsters together, and saved Asgard together. Eventually, Loki's true nature began to shine through. He was the god of mischief, and sometimes a good prank is hard to resist. What's more, pranksters often need to escalate their antics, which often leads to pranks becoming tragedies.

By the time they became adults, Loki was fully entrenched in his trickster role, while Thor was the hero of the kingdom. Loki resented his brother and did his best to dog his heels, doing everything from being a minor nuisance to casting love spells to actively working to straight-up murder Thor. Thor, for his part, was more than willing to respond in kind.
1. Peter "Spider-Man" Parker and Harry "Green Goblin" Osborn

Brothers make for good drama, but best friends may be even better. Peter Parker, eternal wallflower and hopeless nerd, had a crap social life. The big man on campus hated his guts, the girls wouldn't give him the time of day, and the teachers were all too eager to encourage him to become a teacher's pet. Eventually, Harry Osborn arrived, and they struck up a casual friendship. Harry would tell Peter's tormentors to back off and leave the poor kid alone, and Peter would help Harry with his homework. By the time they got to college, they were best friends.

The wrinkle comes because of Harry's father Norman. Norman was the Green Goblin, Spider-Man's archenemy, and the death of Norman broke Harry's mind. He blamed Spider-Man, and blamed Peter for not revealing Spidey's secret identity. He became a new Green Goblin to battle Spider-Man. When he eventually found out that Spider-Man was Peter Parker, any chance of rekindling their friendship evaporated. Harry wanted revenge, and he would stop at nothing to get it.

Or, so you would think. In a surprise reversal, right when he had Spider-Man at his mercy, Harry spared his life. The fond memories of their friendship turned his hand, and Harry died soon after.