Sonic X

Sonic X (ソニックX Sonikku Ekkusu?) is an animated television series, featuring video game hero Sonic the Hedgehog and loosely based on the storylines of the Sonic Adventure series, with a bit of Sonic Battle as well. Its rated genres are: action, adventure, sci-fi and comedy. It was animated and produced in Japan by TMS Entertainment with the partnership of SEGA and Sonic Team. It was released in Japan in 2003; that same year, 4Kids Entertainment obtained the license in a joint effort between 4Kids and Viz Media (it was formerly with ShoPro Entertainment before ShoPro and Viz LLC merged into VIZ Media) & distributed by FUNimation. It is also broadcasted in Europe, Australia and New Zealand, Brazil and Latin America by Jetix, and in Canada by YTV.

Series 1 (Season 1 and 2)
During what seems to be a routine attack on Doctor Eggman's headquarters to rescue Cream the Rabbit and Cheese the Chao, Sonic and his friends are caught in a massive and mysterious explosion that transports them to what, at first, appears to be another dimension. Separated from his friends, Sonic eventually finds himself in custody of a twelve year old boy named Christopher Thorndyke, who saves Sonic's life after he nearly drowns in his pool. Chris lives in a lavish mansion, funded by his two celebrity parents, with his inventor grandfather, Chuck. Chris aids Sonic in locating his friends, and it is not long before Dr. Eggman makes his presence known. As Sonic and Eggman race to collect all the Chaos Emeralds (Sonic wants to use them to get home to his own dimension, and Eggman wants to use them to conquer this new world), Chris must deal with the stress caused by having parents that are too busy to bother taking care of him. The first 26 episodes focus on Sonic and the other's adjustments to Earth and eventually, all of the Chaos Emeralds are retrieved and the chaos power warped parts of their home planet to Earth (like Angel Island and Mystic Ruins). On the second half, the show focuses on the plots of Sonic Adventure, Sonic Adventure 2, and a bit of Sonic Battle. In the end, Tails and Chris' grandfather invents a dimensional portal to send Sonic and the others back to their own world, but before Sonic leaves, Chris kidnaps him because he does not want Sonic to abandon him as he feels his parents did. Eventually, with the help of Sonic, Chris comes to terms with his feelings and Sonic returns to his own dimension. However, Chris vows that one day, he will see Sonic again.

Series 2 (Season 3)
It has been six months since Sonic and friends returned to their own dimension. On Chris's planet, it has been six years and Chris is now eighteen and seems to have a relationship with Helen. He has been working on repairing his grandfather's dimensional portal. In Sonic's world, a new girl named Cosmo arrives on Sonic's planet, looking for the legendary one who can wield the powers of the seven Chaos Emeralds. Sonic, having been nearly defeated in outer space by a new enemy called Dark Oak, scatters the Chaos Emeralds across the galaxy, in order to prevent Dark Oak from using their power. When Chris uses the dimensional portal, he suddenly finds himself in Sonic's world. His age has regressed all the way back to the age he was when he first met Sonic; however, Chris still has all his memories of the years he spent repairing the dimensional portal.

Chris learns that to Sonic, only six months had passed. During their reunion, Dark Oak and his Metarex Army attack Sonic's planet and steal the "Planet Egg" from it. Without the Planet Egg, all the trees and plants on Sonic's planet will wither and die. Sonic and his friends decide that Dark Oak must be stopped, and they venture into space to retrieve the Chaos Emeralds.

This series is similar to Sonic Heroes and Shadow the Hedgehog such as Shadow surviving and being released with memory loss for the former and the common Metarex looking like the common Black Arms for the latter. After many run-ins with Dr. Eggman, and the pursuing Metarex Army, Cosmo's dark secret is eventually unveiled: She has been an unwilling spy for the Metarex all along, and the Metarex themselves are actually part of the same race of autonomous, anthropomorphic plants that Cosmo is of, having twisted and modified their bodies for combat after war overtook their planet. They now must depend on the energy of the Planet Eggs to stay alive. When the Metarex enact a plan that could destroy the entire Universe, Cosmo sacrifices herself in order to save everybody with the help of Super Sonic and Super Shadow; much to the grief of Tails, who had fallen in love with Cosmo during the course of their adventure. It is Tails himself who must kill Cosmo in order to release her power, which would halt the advance of Dark Oak and return him to his benevolent form. Her essence is manifested in the form of a seed, which Tails later cultivates.

With Metarex destroyed, Eggman builds an invention that sends Chris home and Chris accepts, willing to leave all his friends to return home. Soon thereafter, Dr. Eggman revives his previous rivalry with Sonic, albeit a light-hearted one. The series ends with unresolved cliffhangers, such as the whereabouts of Chris and Shadow (although the Japanese version reveals Shadow is alive, depicting him looking at Molly's memorial).