This is an article I have written on this much-debated topic: whether or not The Joker has any possible or real feelings for Harley Quinn.
It is heavily biased from my own perspective; I have followed this pairing for many years and have an enormous passion for it. However, I have attempted at all times to be true to the characters and not pull beliefs or theories from thin-air, basing them instead on established canon and keeping any speculation firmly within character. The true natures of both these villains is important to me and I would not wish to trivialise them by skewing them to suit my own opinion.
I hope you enjoy it, whether you agree or not!