This was written as an author's note on one of jarec's fanfictions and is reproduced with his permission.
Just Like Having A Shark Love You
This is my own take on the Harley/Joker relationship.
Does he love her? Yes, but that isn’t the question.
The question is, Is that a good thing for her?
The answer is NO.
Having the Joker love you is exactly like having a shark love you.
In both cases, you are subject to the attentions of a creature who has no
experience of love, doesn’t understand what it’s feeling, has no mercy or
pity, and whose ‘default setting’- if you will- is murder.
Not a safe situation, as can be seen from his rapid shifts in mood.
Psychos CAN love, just look into the history of some of the more prolific
serial killers.
Also consider - more evil has been done in the name of love than has ever
been done for hate.