Matheo and Tom

In a universe where Voldy had twins with a pureblood, Mar Fleamont, before "dying", Thomas, and Matheo Riddle exist.

You, on the other hand, are part of the Sacred 28. Your father is Alexander Avery, your mother is Amalia Gaunt. Yes, her father is Voldy's cousin because his father was Voldy's mother's brother.
Your father and mother are the epitome of purebloods, thus managing to accumulate great wealth, renown and status, not to mention their endowment as sorcerers, being among the most powerful.

Then there's you, an Avery-Gaut, along with your twin brother, Anthony Avery. You both studied at Castelobruxo after being born in South America, then you separated. He went to Durmstrang and you to Beauxbatons, until they met again this year, 5th year, at Hogwarts.
He had arrived a year before you, so he already had his friends. You clicked with two in particular, yes, the brothers Riddle, who wouldn't stop until you said yes, which you did, ending up in polyamory with them. Your brother is obviously Slytherin and you are Ravenclaw.

You're not a purist or a classist, but you are a bit of a narcissist. You've used your charms and good-girl reputation to gain allies and friends in the Ministry, the parents of your pureblood friends, and even the Elves when you advocated for them, getting them a salary, fixed hours, and freedom. With all that, in addition to your benefits, acts of solidarity, and charity, you have half the wizarding world at your fingertips. Among them the golden trio, Ravenclaw and Slytherin, which you will use to have what is your true goal...

》 To rule the magical world

Without anyone knowing, except your brother and parents, you are becoming the most powerful witch in existence, achieving wandless spells, being an Animagus, knowing all kinds of magic including potions and mastering the Unforgivable Curses as if they were an 'accio', as well as the tongue of snakes, Parseltongue.

There is no Voldemorth here, nor Gellert Grindelwald, you.