I don't think that I'm the only one who can admit that they like romance. I love the stuff. No, you will probably never find me walking over to the Harlequin Romance section of my local bookstore to pick something up, but when there is a romance element woven throughout a story without completely overpowering the plot, I am all for it.
I have read my fair share of young adult novels. I have seen so many different types of love interests that I sometimes dream about them (I don't, really...I promise), but while some get my heart fluttering like a wild thing in my chest, others make me want to shut the book and never open it up again.
The one young adult book that got me into reading is, no surprise here—Twilight. Ah, yes. The most hilariously controversial book of recent years. The controversy being between the fans and the non-fans, of course. I'm not going to get into my opinion on the book, but I am going to talk about one character that makes a whole lot of appearances, some even unknown to our main character: Edward Mason Cullen.
At the beginning of the book, I feel like Edward knew what he was doing. He was controlling himself. He told Bella to stay away from him (because he was going to eat her). Everything was going well. I loved him. I was eating up every word he said. I wanted to jump into that book and never come out. I wanted to live in the rainy town of Forks and listen to Debussy in his bedroom—I was so into it. I was also roughly twelve years of age, but we'll leave that out of it. I'm not sure when it was, but there was a part of the book where Edward completely changed. It came out of nowhere. He became this possessive-stalker-beast and it was just ridiculous. I would've loved it if it took more than a dinner date for them to fall in love with each other, but that's really all it took.
That's one thing that writers need to keep in mind when writing love interests. Hot and cold is not attractive. There is no reason that your Love Interest needs to be a complete ass one day, and be a little Romeo the next. There is no reason for it. And if you're Love Interest is going from being a cold, introverted person at the beginning of the book to a more open and kind person at the end of the book—that's fine. However, you need to make sure that it doesn't happen over night. I hate reading situations like that. You need to show the growth and change throughout the entire novel. We don't want our bad boy becoming soft and sensitive, though. Don't completely change who they are. If you have a bad boy in your story, great (so do I) but you need to make sure he comes off as a real character and potential love interest.
Your MC may be attracted to his looks or confidence, but they aren't going to be fooled into loving this asshole just because you want them to. Trust me. Forced romance is painfully obvious in a lot of stories and that's something that I don't want in my stories, and I bet you don't want that either. You need to create characters with spark and chemistry and you need to make legitimate reasons why they would love each other or live for each other or willingly die for each other. You need to. There is no question about it.
Bad Boy's aren't just steel and metal. Experiment with your character. Pull back his layers and see what's really hiding underneath. Don't rip off all of his armor in one scene, though. First, remove his helmet. Let's see how he thinks. Then, remove his shield. Let us see him say something other than a rude/sarcastic remark. Make us believe that your characters love each other. Once you do that, then you can do anything.