Perhaps you’ve heard of her. She had a few rather large hits a few years back.
Something about vampires.
Something, more importantly, about PERFECT vampires. If you ever have the addictive misfortune to pick up a Twilight book, you’ll see, in the first few pages, exactly what I mean. The characters have zero flaws. None. Which makes the characters seem more whiny than relatable.
When you piece together your characters, it is important in the extreme to make sure that they are flawed. Not overly flawed. Train wrecks are fun to read about, but they get exhausting. You want them just flawed enough that they get in their own way once in awhile and provide conflict and interest.
A perfect example of this can be found about 150 or so years ago, in the form of Jane Austen, who wrote some of the most beautifully flawed characters of all time. And, since I used Twilight, a “love” story as my first point, lets counterpoint with Pride and Prejudice.
Edward is completely, totally and in all other ways wrapped up in Bella. She is his everything, all the time. he has no concerns in the world other than her happiness and safety. It’s all very swoony, but it also makes him a bit one-dimensional because, besides some rather stalker-y behavior on his part, he doesn’t have anything wrong with him. He’s perfect.
Darcy, on the other hand, is privately generous, loyal, and fierce in his emotions, which all make him incredibly swoon-worthy. However, he is outwardly reserved to the point of rude and overly-concerned and prideful of his stature and title. The latter is his major flaw, the thing that gets in his way of his love for Elizabeth and threatens to ruin his happiness and hers, forever. It is that flaw (as well as Elizabeth’s own personal pride) that provides the necessary conflict to the story. It isn’t even necessary to have an actual villain, because Darcy gets in his own way enough.
Flaws add interest to a character as well. Returning to Pride and Prejudice, where would we be without the pretentious Mr. Collins, the ridiculous Kitty and Lydia, the forward awkwardness of Mrs. Bennet and the horrifying cattiness of Mr. Bingley’s sisters? Even the naivete of Mr. Bingley and Jane Bennet, while certainly a flaw, lend their characters an endearing quality that makes readers want to root for them.
Perfect characters are no one’s friend. They are boring, and unless your target audience is simultaneously teenage girls and 45 year old wives, you really aren’t going to sell many books with them.
On the other hand, if that is your target audience, I hear half vampires and werewolves make great couples.