Her reflection in the mirror had horns!

...Wait.

That wasn't her.

Not quite.

The resemblance was strong, but the figure in the mirror was older-- an adult.  Dressed more daringly, with skull-and-chain themed jewelry.  Also with wings.  And fangs.  Wreathed in shadowy fire.  And possessed of an evil smirk.  (Seriously, there was no doubt about it-- the smirk was evil.)

"So," the mirror said.  "It is time."

"O-okay, this is clearly a dream. Just a dream," Elizabeth said as she stared at the mirror.

"Aw, don't be like that," said the reflection.  "This is important!  You are my heir!  My next incarnation!  Your power has awakened, and your destiny calls!"

"I think I'm going to go back to bed and wait for me to wake up," Elizabeth said.

"Hey, wait!  WAIT!" shouted the reflection as she turned.  "Don't do that!  For one thing, your horns and tail aren't about to go away!  You're gonna wreck your bedding!"

"Okay, fine, explain everything then," Elizabeth said.

"Well, like I said, you're my newest incarnation," the reflection said.  "You're the heir to my dark powers, destined for conquest and rule!  Your power has now started to awaken, so naturally your body has changed to reflect that.  You're strong, you're tough, you have horns that mark you as a noble, and an incredibly fashionable tail!  In addition, you'll start to have the power of Shadow Magic, and that will only grow as you grow.  Congratulations!  You're awesome!"

The figure did a little display of applause and arm-pumping in celebration.

"...and it's just in time, too!"

"In time for what?" Elizabeth asked.

"Well, with any luck, for you to achieve great power, conquer your foes, make them your servants, that kind of thing," said the reflection.  "...and also to not die when your enemies come after you."

"Enemies?" Elizabeth asked.

"Yes," said the Reflection. "For one thing, there's our former servants.  By which I mean beings of tremendous power that we conquered and subjugated.  You're going to want to get on with conquering them, because, uh, they aren't subjugated any more, and they might just hold a grudge over the whole 'conquest' thing from last time around. Also, defeating them will get you more power, and you're going to need that... for one thing, they are all probably stronger than you right now.  So, y'know, be smart.  Treachery and betrayal worked really well for me last time, but since they might remember their past lives, they'll probably remember what happened last time, and won't really trust you.  But you'd better work something out.

"...because, uh, also, there are heroes who have also been reborn now that my heir has come into her power.  And there's really no question that the heroes will come after you as soon as they can.  And they're also going to be much stronger than you are now.  So you'll need a lot more power."

"Wow, I wonder what I ate to get a dream like this? My subconscious seems really angry today," Elizabeth said.

"Hey, are you ignoring me?" asked the reflection.  "The next me shouldn't be so stubborn about listening to advice!"

"Well, I'm not a treacherous person and I don't think I'm about to start now, just because you tell me to," Elizabeth said.

"Fine," said the reflection. "Be that way... I said I was, anyway, but you probably can't get away with that.  They'll be on to you.  You'll need to find a better way, but be smart.  Heroes win if you go on raw power."

"So, heroes are going to try and kill me just for existing? That doesn't sound very heroic," Elizabeth said.

"Well, what can I say?" said the Reflection.  "You're the Shadow Queen now.  Also, some of them could very easily be after, well, revenge..."

"Just how evil were you?" Elizabeth asked.

The figure paused.

"Evil?" she said.  "Well, I mean... I guess I was ambitious... all right, ruthless, too... not any more cruel than I had to be, though!  It's a dangerous world out there-- all kinds of monsters and heroes always looking to cut you down!"

"Then why would they want revenge on me?" Elizabeth asked.

"Well, some people just won't let go of grudges," said the reflection.  "They're just so petty!  But then, on top of that, as Shadow Queen, you're a threat to them.  Heroes get very proactive these days, you know."

"What does that mean? They go out looking for fights all the time? I though that's what they're supposed to do," Elizabeth said.

"Well, go looking for people who they know are likely to become a threat to them, might wind up conquering the world, whatever," said the reflection.  "Don't you keep up on this stuff?  It's been Gritty Cold-Blooded Sociopath Heroes for a while now."

"How am I supposed to know that? That's fiction. No one in the real world does that," Elizabeth said.

"Well, believe me or don't, but the beasts we conquered are out there, and they're waking up now, so you're going to have to be ready," said the reflection.  "You're going to need to figure out some way to survive this... you can always ask me for advice, y'know."