Game on

Chapter 1: Intro

"Given how you're phrasing it, I will..."
"Become as powerful as any other god? Yes. But what is interesting, right now, is that you aren't. And thanks to that, you can still easily interact with the mortal world directly, as opposed to us gods. What we're proposing is for you to be reincarnated in various mortal worlds, where your role would be to assist Fate's chosen heroes. They would still probably triumph without you, or at least they all have the potential to conquer, just as you had, but still your help could save time, suffering, and even life."

"How will the wizarding world fare against those neo Death Eater without me?"
Death chuckled at the nickname, and answered " Your help would end them faster, but even without you, the muggleborn will eventually act and drag the wizarding world into the XXI st century after banding against the True Wizards."
"And about these... Death Islands... Would I find my friends? My family?"
"Well, Dumbledore has already chosen to be reincarnated, but most of the other dead you know are still there, following your life. They all love you, you know." said Death with a smile – since he'd guessed the little girl would become his master, he'd followed her life with interest, and as such, interacted a lot with her dearly departed
"Most? What do you mean?"

The tall man nearly held his breath, he knew she'd ask the question – and now, her entire future would be wagered on the answer "Your mother's protection had a price... As I told you, we gods can't interact too much with the mortal realms. One of our loopholes are pacts. Your mother's plea reached us, and a pact was made to protect you, thus making you the Girl Who Lived."
Harriet felt fear for the first time in a long time and despite being dead, breathing suddenly became harder "What was the price?" she managed to ask in a whisper

"She accepted to be thrown in Purgatory for eternity." announced Death somberly "Thus forfeiting any after life on Death Islands, or any reincarnation..." the green eyed girl closed her eyes, but then, Death added "There is one way to change this."
"How?"
"Mortal souls can get out of the Purgatory only when guided by an immortal. If you go with the gods proposal, once you're powerful enough you'll be able to go and retrieve her. It won't be easy, and it'll take a lot of time to get to that point... but you'll be able to do it."
"I'll do it."
No hesitation – as he'd predicted. Death withheld a sigh.
The girl that was now his sister in powers if not blood had chosen a hard path, as even for the higher gods the Purgatory wasn't easy to navigate...

¤.¤.¤

Her decision made, Harriet followed Death out of the whiteness, into a large room filled with various beings- some humanoids, others not, all sharing a powerful aura of eternity. The gods, guessed Harriet.
"Welcome back, Death. Welcome, Harriet." said a seemingly young girl with pink bubblegum hair and silver eyes "I am Fate!"
Harriet eyed the goddess, wondering how to react. On one hand, it was her fault she was now an immortal protector of heroes; on the other hand, if she hadn't meddled, she wouldn't have this chance to save her mother's soul.
Finally, she smiled back "Nice to meet you all."

"So let's get this show started!" shouted a young boy nearby "I'm Chaos, and I have a proposition for you!"
Harriet gave a quick look at Death, wondering what she should do. Thankfully, Death, having understood the unasked question, gave a small nod.
"What is this proposition, Chaos?"
"A Game!"

Seeing the new addition to immortality wasn't following what Chaos was saying, Peace explained softly "What you have to understand is that so you can play the role we are suggesting, you cannot grow too strong for the mortal realms. One option for this, is to play with reincarnation, you'll have your memories, but your powers would be restrained at each reincarnation. This is where our dear Chaos proposition come into play..."

"Yes! To make things more interesting!" the exuberant young boy cut back "I can force your soul to adapt into a new form... You'll loose a lot of your actual powers, but instead, gain a lot of potential power!"
"How so?"
"By making your life into a game! In each new world, you'll loose your previous powers, thus fulfilling the 'not too powerful' clause, but thanks to the gaming interface you'll grow powerful quickly in each new life."