Elena's story, yes.
She is a high mage for Grand Chase, then is bribed with unbelievable power by Kaze'aze and secretly joins her. She's then discovered by Grand Chase, beaten, and forced to revert to her second form: Kamiki. Now, either this is a twisted Elena form(the unbelievable power part), or Kamiki existed before and used Elena as her puppet to get information, but either way. After Kamiki is defeated, Elena is brought before the queen of Serdin/Kanavan(can't remember, don't care) and confesses to being bribed.
The fact is: she was bribed and gave in to the bribe, which a regular, good-hearted person would have surely refused. Unless she was forcefully hypnotized into accepting the offer against her will, I conclude she's a greedy little power-hungry female dog. If the second applies, why did she admit to only being bribed and that she wasn't forced to do crap?
Elena is evil because nTreev/KOG made her that way. No one likes her anyways. Therefore, sign me up, yes.
IGN is Yirocu. Need you know more?