Somehow, I feel most people don't take Harle for what she really is. She's a much deeper character then people would realize.
Firstly, many people debate that she is another clone of Schala. That makes sense because of a few reasons:
1. She gets the same fortune telling as Kid, a comfirmed clone.
2. She was made by the Dragons. Now, the Dragons had access to only three life forms: One is Lavos. Making a Lavoid clone would totally mess up their plan, because FATE would have it terminated at once. Same for a Dragon clone, once FATE realizes there's another Dragon, she'd of had it killed. Hence you only have a human left. That human is Schala, the only human the Dragons had access to.
Now, another matter is how deep she is. Her situation is a very painful one: She's a Dragon AND a human. She's half and half of two races that cannot co-exist, thus she has an internal conflict. There's also the matter of Serge-she cannot disobey the Dragons, but she loves him profoundly. That's why if you choose to say you'd choose her over the world, she won't believe you. She ridicules herself and hates herself very, very much. To her, her very life is a joke. That's why she's dressed as a jester, she doesn't just want to hide her identity, she thinks of herself as a person cursed by destiny. Either way she cannot win, and every true emotion she might have at anyone won't matter. Fate mocks her, and that's why she dresses up as a clown.