Interestingly, despite being a creation of the Ice King's imagination, the Ice Queen is far more cruel, evil, and aggressive than he is. She uses much more violent and complex means to get her way than the Ice King does, such as tormenting Fionna with a wild scheme in order to put her out of commission, and leaving her free to obtain Prince Gumball, while the Ice King would usually break in through a window with a cheesy phrase.

And you are inside her castle because you were kidnapped by her