WMG / Sonic X

Helen is the reincarnation of Maria Robotnik.

Both of them have blonde hair, blue eyes, and are both medically affected in some way.

The hostile species that invaded Cosmo's home planet was the Black Arms.

Which would make their leader Black Doom the Greater-Scope Villain of the Metarex Saga.

Sonic X is a Self-Insert Fic

In reality, Chris Thorndyke is a fan of Sonic series, who has friends, and his family, including his prestigious parents, do love him, even if they're not around to show it, he just finds the world around him boring, and he just happens to be fascinated by the Sonic the Hedgehog games and characters, as it’s what gives him life. He writes his own story about Sonic and his friends coming into his world where he befriends and has adventures with him.

This would explain the adaptational character changes in the characters causing them to be out of character from the Adventure games (such as Sonic being more of an Aloof Ally, Knuckles being more gruff and gullible and Amy being more aggressive), why some of the story arcs like the Chaos and Eggmoon Saga were rushed/short, why the show's boss battles are nothing more than Curb Stomp Battles, why the show constantly insert random human characters with full-blown personalities, why some plot points are just added as the series goes on and forgotten about (ex: Two Chaos Emeralds creating shockwaves, Eggman finding out he was born on Earth, Mobius and Earth originally being one) and why the show has a fan-ficy type feeling as fans pointed out. There's also the Metarex Saga where Chris is at his most competence, and most of the characters were more out of character than in the earlier seasons, and then there's the sci-fi theme, probably wrote it when Chris was in his teen years when he came more of a Trekkie.

Perhaps this version of Chris isn’t from Station Square (which is a city from Sonic Adventure), he’s from either the four cities that inspired Station Square which are New York City, Chicago, Philadelphia and Boston.

The name of Sonic's world is Mobius.

Because why the hell not?

Sonic X is Shadow's self-insert fic.

MARIAAAA!

Eggman is from Chris' world.

This makes sense as Eggman's grandfather was a respected scientist in the human world, at least for a while.

• Why is this a WMG? Eggman treats being born in the human world as a near-unshakable fact after the reveal that his grandfather is from there. It's how he ended up in Sonic's dimension that remains a mystery.

The seed Sonic gives Tails at the end of season three is Cosmo reverted to an infant state.

Chaos Control (or in the Japanese version: Chaos Regeneration) was effective at saving Cosmo, unbeknownst to Sonic and the others, but it went way too far back. Sonic and co. will have an interesting time whenever Cosmo reaches the actually looks like a baby Seedrian stage of growing up.