"The Peverell and Gryffindor lines are closely linked to you through blood, and it would take only a slight modification of your blood to allow you to claim them. The Slytherin line could be yours through old family magics called the right of conquest, whereby the conqueror of the last of a line can lay claim to that line's family magics, provided they didn't initiate the conflict that led to the death of the line. This includes titles since they're based on family magics."
"So because I defeated Voldemort when a child… wait, wouldn't I have that last one anyway?"
"Riddle didn't truly die."
"Ah."
"But! That's exactly the kind of minor adjustment to magic that I can get away with. The difference between dead and not alive is close enough, and the age of your soul gives me enough wiggle room in regards to you being of age to claim."
She took a deep breath before continuing.
"Now, you're only getting one of them, so you're going to have to choose. Any thoughts?"
"Well, screw Gryffindor. I'm a Slytherin, through and through. So it comes down to Slytherin or Peverell. Peverell would grant me greater overall political acceptance. I wouldn't have to worry so much about being immediately labelled a Dark Lord by a third of the wizarding political elite…"—Harry stretched his chin—
"…On the other hand, Slytherin would grant me immediate kudos with the very enemy that I'm trying to fight. Any death eaters or allies of Voldemort that I can bring to my side would be a double victory, simultaneously denying the enemy resources while boosting my own. With Peverell, I'd have to play a zero sum game with Dumbledore for allies—A moment of silence passed—Slytherin would also grant me special privileges at Hogwarts… I assume?" he finished, uncertain.
"A few, yes," Fate conceded.
"And it would also give me a mission to rally people around other than just 'defeat Voldemort'. The ideals and beliefs of Slytherin house are nothing like what they should be. Ambition and cunning does not equal evil and bigotry," he mused.
Fate smiled.
"Also…, and I think this is the real kicker, by claiming the tile of Lord Slytherin through right of conquest I can easily demonstrate that I am the true child of prophecy to who ever I please, whenever it is necessary."
Fate clapped, and Death just sat there, relaxed, and looking incredibly smug.
"Well done young champion, very well thought out. Your brother never demonstrated even a hint of similar strategic insight."
He smirked. "Well, he is a Gryffindor."
Fate raised a warning finger. "That's as well as maybe but remember not to let house rivalries detract you from strategic necessity. There are Gryffindors it would do you well to bring to your side.
"…Granger." The Dark Lord's memories of the brunette muggleborn were impressive. Hell, she practically carried his brother's team, despite being four years mentally younger than him.
"Yes her, definitely. But also remember my warning. Any advantage, as quickly as possible, for as low a cost as possible."
"Right. Not to mention she grows up to be hot as hell."
Fate frowned.
"I'd advise against falling into he same trap as your brother and collecting too many witches of questionable usefulness around you. They could easily become a distraction."
"Right. So I'll only collect the useful ones. And distractions… I'd prefer to call them strategic team building exercises." He tried his best to look as innocent as a pile of rags and bones can.
Death grinned from ear to ear while Fate looked resigned.
"Well, I've just spent twenty years in hell, yes? I'm not holding back on this second chance. I will do everything in my power to make sure the primary objectives are achieved, which at the longest should only take five to ten years, fingers crossed. I fully intend to make sure the final hundred odd years of my life are as satisfying as possible."
Death spoke up. "Mister Potter, so long as you achieve your primary objectives, I personally don't care if you become a dark lord and destroy the whole of Britain."
"I'd be a bit miffed, but couldn't actually fault you," Fate interjected, "so long as Riddle dies and the prophecy is fulfilled, you have a free pass.
"Excellent, because I fully intend to ruin a few people's lives."
The trio continued to discuss minutia and tactical and strategic options for some time, before Fate and Death waved Harry on his way and his soul was flung back through the veil.
......
On July thirty-first in the year 1988, eight-year-old little Harry Potter sat bolt upright, banging his head on his cupboard ceiling.
'Oww', he thought, rubbing his hand on his bruised forehead. He felt a metal band on his finger. Closer inspection revealed it to be the noble head of house ring of Slytherin house. A manic grin spread across his face like the opening to the gates of hell.
"Well, hello world, I'm baaaaaack."