This isn't me saying YOU MUST SHIP THIS, it's purely so I have an answer on-hand when I get asked, which I inevitably will, why I ship them.
Why Megamind and Rapunzel? Why NOT Megamind and Rapunzel? Seriously, do people at Dreamworks and Disney not TALK to each other? These characters have such AMAZING potential together, it's hilarious to me that their films came out so close together, yet were from two different studios.
Okay, I love opposites attract things, but in real life, I find a lot of times, people with more similarities work better. That's the beauty of Megamind and Rapunzel, though! They come across as total opposites at first, but they're really got a ton of compatable traits.
At first, yeah, she's this super-sweet princess and he's an evil super villain. And that's GOOD, because they help each other find balance. That said, though, Rapunzel isn't sugar-sweet-princess-rainbows. She's got flaws and she is perfectly capable of being a tough cookie who does NOT take anyone's shit. Megamind, on other hand, is far from truly evil. He's not just a softie, no. He's got a horrendous ego and a bad attitude, but that goes so well with Rapunzel's lack of patience for people's shit. He's also INCREDIBLY CHILDISH for at LEAST 70% of the film, which not only works well with Rapunzel's wide-eyed, new-to-the-world ways, but actually leaves her as the MORE MATURE one sometimes. How scary is that? Furthermore, Megamind IS shown to be sweet. He's just not ridiculously so ALL THE TIME.
You know who else has a horrendous ego and a bad attitude and maturity issues and is sweet but not overly so all the time? Flynngene Fitzrider. Just saying.
So there's the general meshing; how they play off each other and how that works so well. Let's look at why they'd be attracted to each other.
Rapunzel is really pretty, for a start. Megamind, on the other hand, would be a really odd sight to the typical eye. But Rapunzel has an artist's eye, and would doubtlessly be intrigued by such a unique specimen. More importantly, she's definitely the type who would find beauty in one she loved. She's a Disney Princess, it's a Thing.
But blah, that's superficial stuff, anyway. Megamind, though a derp, is truly intelligent, and that would draw Rapunzel in, as would his dramatics. She'd be so interested in his grand behavior and over-the-top...ness. For Megamind... Rapunzel is sweet, patient, and quite tolerant and forgiving. These would definitely be a big deal to him.
Would Rapunzel love that Megamind was a villain? No. Would she really see a ton of harm in him just causing some public disruption while mostly just trying to kill a man he KNOWS IS INDESTRUCTIBLE? No, she wouldn't. No more harm than one would find in a thief.
Moving on! The more they got to know each other, the more Rapunzel would find Megamind's silliness endearing, and his sweet moments attractive. Likewise, Megamind would be drawn to Rapunzel's creativity, because it's in such a different vein from his own. He would definitely enjoy her feisty side, too.
And then we get to the stuff they'd fall in love over; the stuff they have in common. Though in different ways, as mentioned just before, they ARE both creative people. They MAKE things. It's their shared passion. They're both sheltered, even if Megamind might not realize he is, and they both have things they'd rather keep secret and histories that aren't the happiest, even if Rapunzel isn't initially aware of how bad she has it in the tower. They're both very curious and love learning, both are at least somewhat childlike fairly often, and they both really do love being part of the world around them, being in the center of the action. They are both, at their core, good people, and they both develop very strong emotional bonds very quickly. In a literal sense, they weren't made for each other, but in every other sense? I'd say they are.
(Entry originally posted to my DW journal.)