There is no princess
Therion is a swedish band. They started out as a black metal project, but the guy yodelling lost his voice, when he caught his neck in a door. No matter what would you imagine, he actually caught his neck in a revolving door, but on the hinges side. Then he thought of going to save a princess or something, but he remembered the second paragraph of this article, where someone writes he ain't savin' no freakin' princess. So he wanted to attempt a mass suicide in the band, something between emo, gothic ideals and Jonestown massacre, but that was lame since his music wasn't on that stuff.
What about the princess?
So, continuing the princess idea that this article strongly denies, he wenchnapped lead singer from nightwish and sent a blow-doll for the last concert, "End of an era". Luckily enough, the other band members thought that Tarja quit her job as the primary *ahem*, singer (seen in her aspect, the doll) and decided to fire her due to bad singing.
So the guy from therion fed her up (check the picture on Wikipedia's smartheads page, about therion) and she got really fat. He said it's for the singing, but the underground religions and occult Therion plays on, really nominate her for a BBW.
the princess Tarja in the new lineup, they radically changed the style, singing about religions, occult, gods, and magic. Oh, and also mystic and mumbo-jumboo voodoo. Did I mention that a bunch of them even have a sect, called Dragon Rogue?