When you're a succubus with a genie sister, using magic against each other is inevitable... Even more so when one was adopted.
Venus: "What's wrong, sis? Can't fly free from my toes?"
Mercury: "Venus, let me go!"
Venus: "With you getting rubbed all over like this, it looks like you'll have to call me 'Master' for a while~"
Mercury: "As soon as you make your third wish, I'll make you wish Mom never found me!"