My coworker and I raised the subject of the 'ugly-pretty' face - models, actors, singers, etc who have a very pronounced 'flaw' in their features (sometimes more than one) that makes them stand out, but on its own isn't attractive. It's the combination of the flaw and the face that make the magic happen for fans. Some female examples of this are Angelina Jolie, Uma Thurman, and Julia Roberts. Male examples are Robert Carlyle, Benedict Cumberbatch, and Matt Smith.
So what makes these people or their characters desirable?
I discovered a good example of this in the Hallmark mini series The 10th Kingdom. The character of Wolf began the show as a desperate, over-enthusiastic neurotic. His desperation didn't do much to attract the attention of his beloved Virginia. It was only after he got control of himself and projected confidence that she succumbed to his charms. So did many fans.
The same can be said for Rumpelstiltskin in the ABC television series Once Upon a Time. Before he became the Dark One, Rumple was cowardly and repulsive - so much so that his own wife left him for a more confident man. With the injection of power, his confidence rose, creating a character who no longer cared what others thought of him. Fans were drawn by this new magnetism - and even more so when Rumple attracted the unlikely admiration of Belle.
This brings me to another point, brought up so well by Brianna Shrum on twitter. She's attracted to characters who show desire for or are desired by other characters. We've often seen this point proven in the dating world when a person is in a relationship. Suddenly they become much more attractive and get more attention than when they're single. It seems that desire breeds more desire.
A fantastic example of this is the Sherlock episode A Scandal in Belgravia, which Brianna referred to in her tweets. In this episode, we see Sherlock flustered by an attractive woman, which usually does not happen to Sherlock. The reason for his reaction to Irene Adler has more to do with the quality of her mind than the quantity of her body (which she displays freely). We all know Sherlock is attracted by another's intelligence or the appreciation of his own (i.e. John Watson), but Irene takes it to the physical level.
I believe the appeal of the desired goes deeper than mere popularity. When a person is desired, it affects them internally. They feel more confident and they display a different side of themselves. Like with Sherlock, they show off. (I believe the term is 'peacocking'.) Instead of facing the world as though its judging them, they parade as if it loves them, because they've tasted that love and attention already.
When a person doesn't worry about being judged, they can be themselves, and often the best of themselves. So what we're really attracted to are their best qualities shining through, unhampered by self-consciousness.
A Scandal in Belgravia not only showed us Sherlock's desirable side (which many of us saw before that), but also his vulnerability. Letting his guard down with Irene leaves him drugged and disoriented in John's care. Seeing an independent, confident person show weakness or softness plays upon our sympathies and makes the other person seem more human. With women in particular, vulnerability brings out the need to nurture, to be depended on, and, therefore, it's attractive.
Showing vulnerability is also a strength of character, since a person who shows both strength and weakness must be honest with himself and others. It involves quite a bit of trust as well. Only strong characters risk opening themselves up to the possibility of betrayed trust. Strength is very attractive.
Those are a few traits that make characters desirable to me. If you have further insights, please share them in the comments. Thanks!
You might also like the articles I read before I wrote this.
A Batch of Cumberbunnies by Jennifer Proffitt
Unlikely Male Sex Symbols an article from The Guardian
Love vs. Lust: An Analysis of A Scandal in Belgravia from Sherlock Character Analysis on Tumblr