Scarlet is the Bloody Prince’s secret lover/admirer. She found out that for the Bloody Prince to notice her, she must pass the ultimate trial, which is to defeat the Mad King in his game, the “mad king says”. Scarlet was able to defeat the Mad King but the Bloody Prince still refused to even lay an eye on her. (she’s ugly!) And that is the reason why Scarlet is in rage right now and trying to invade Tyria.
It is what it is people.