Edited for punctuation and minor stylistic elements. Hm… well, Misa's character study. Not really much to say beyond that. I've tried to portray her as I think she must be, though this is one of the less validated opinions I have on characters, as far as support from the original goes. So, presenting Misa. Enjoy.
Misa is not as stupid as she lets everyone believe.
Misa knows that her Kira is using her. She knows, even, that what he, and she, does is wrong, evil, murder. She knows that, sacrificing her life twice like she did, she can't have more than a few years left. She knows that he doesn't love her, and never will.
That doesn't mean she doesn't love him, though. Misa knows that.
They say love's wonderful, whoever they are. They say it's joy and life and the loveliest thing to ever exist. They're right, too, Misa thinks. She loves her Kira-kun. He's beautiful, smart, powerful, confident. When she's around him, she feels like nothing can ever go wrong, and even if somehow it did, her Kira-kun would just whisk her away to another world, where they could start over and make everything perfect.
Other people, though, say that love is hideous. Poison, destruction, death. (Misa thinks, sometimes, that her Kira would say that, too.) And Misa knows that they are right. Her Kira poisons her mind, takes her life away with an unspoken wish, controls her thoughts with toxic words. If she didn't love her Kira, she'd have helped L—she could have found him as easily for L as she did for herself, and that would have been the end. The world wouldn't be falling apart, ripped to shreds by Kira's quest to make everything go right the way he wants it. And he killed her career, with just a word; it was the only death her career ever could have had. So Misa knows that they are right.
Misa loves beautiful things. That's why she became a model and an actress, because she could be lovely, and be surrounded by lovely things. And she is, she is lovely, her Kira-kun is lovely, and her life is lovely, too.
Love is destruction, Misa knows, and poison and death, because her Kira is all of those. He uses her to accomplish each thing he wants, uses his poison and her weakness to make their death—a destruction that Misa detests, but won't ever do a thing to stop. Because love is lovely, too, and when Misa's Kira isn't tearing the world apart, Misa's Kira-kun is the most wonderful thing she's ever even imagined.
So Misa keeps going. She lives for her Kira-kun, and doesn't worry about what her Kira does or has her do. She's smart enough to know that she couldn't stop herself from obeying him, anyway, even if she tried. And while she knows that her Kira doesn't love her, she doesn't mind. After all, she doesn't need him to love her, she just needs him to be around and pretend he does. And the power she has from his need of her eyes will keep him by her side far more surely than any love would. So long as Misa has her eyes, she knows that her Kira-kun will never leave, and that's all she wants. She thinks in some things, she is smarter than her Kira, since she can keep him by her so well.
Misa didn't think it would go this far. When she found her Kira-kun and agreed—or decided—to help him, she didn't know how long it would be, how much they'd lose, how many people would die. She didn't think they'd have to kill innocents, people who weren't criminals, or trying to interfere.
Misa wasn't smart enough to expect that. Or maybe she was, and she just didn't know her Kira as well then as she does now.
Misa is smarter than anyone things, and she knows more than she ever thought she would. So Misa looks around, at all the lovely things—her room, her clothes, her jewelry, her self, the picture of her Kira-kun, that she has to look at while she waits for him to come back. The only thing that's there that isn't lovely, to everyone else, is four sheets of notebook paper sitting on the table in front of her.
But, that's only because everyone else doesn't know what they really are. And Misa, with her special eyes and her knowledge that no one else has—she thinks they're the loveliest things of all.