Cosmo

Cosmo is a Sonic X exclusive character created by Sonic Team. It is believed her design stems off Void from Sonic Shuffle.

Cosmo is a fictional character in the Sonic X television series, first appearing in the show's third season.

Cosmo is a female child of a plant-like alien species whose homeworld was destroyed by the villainous Metarex. She is an ally of Sonic the Hedgehog and his friends, and it is widely accepted that her primary purpose in the series is that of a love interest for Tails, the two characters being of the same age and displaying an overt fondness for one another.

Appearance and origin
Cosmo first appears in episode 53 of Sonic X. Her former home world was destroyed by the Metarex before she was born, and she was instead raised on a space colony. She lived peacefully there until the Metarex came and began to destroy her new home, including her family. As Cosmo was escaping, the Metarex planted a tracking device on her. Cosmo also has a device inside her brain which, when activated, allows the Metarex to hear and see everything that she does.

After the attack, Cosmo escaped into a ship and arrived on Sonic’s planet. Tails, Cream, and Amy are the first to find her, and they question her arrival. Cosmo tells them that she is looking for the "legendary hero, that can use the Chaos Emeralds, Sonic the Hedgehog." However, she refuses to tell them any more. Later, while in Tails' ship, she spots Sonic and hops out to greet him. Cosmo pleads for Sonic to help her.

Later in the series, Shadow boards their ship and attempts to kill Cosmo, but Cosmo’s friends manage to keep her safe. Tails especially endeavors to keep her safe, to the point of almost being knocked unconscious. Before Shadow could do Cosmo any harm, a Metarex breaks in and steals the Chaos Emeralds. The Metarex call Cosmo "White Seed", and tells her that she did a good job. Cosmo then remembered that before she escaped from her space colony, the Metarex was planning to use her as a spy.

Knuckles, Tails, and Chris then analyze Cosmo and find that it is attached to her brain; if they get rid of it, Cosmo’s hearing and sight may be lost in the process. Knuckles says that it is best to do that, but Tails refuses to harm Cosmo. Later, Cosmo learns that she can hear the Metarex in her head and falls into deeper despair. While she is in sorrow, Chris tells Sonic that he now understands why Cosmo was able to understand the Metarex language.

In Episode 74, Cosmo runs away, but is stopped by Tails. Their friends then show up and say they are determined to defeat Dark Oak instead of risking Cosmo’s hearing and sight. In Episode 77, Cosmo sacrifices herself by fusing herself with the Dark Oak planet to make it weaker so Tails, Super Sonic and Super Shadow could destroy it and save the universe. At first, Tails refused to, but ended up shooting her with the Sonic Driver, causing his heart to be broken in the process. In an attempt to rescue Cosmo from death, Super Sonic and Super Shadow used Chaos Regeneration, but all they managed to produce was a small seed. In episode 78, when Sonic arrives back on board the Blue Typhoon, he hands this seed to Tails, who collapses with grief as he realizes that Sonic was unable to save Cosmo. However, a small plant is seen growing in a pot in Tails' workshop. Everyone mourns Cosmo's passing and even Eggman seems to show some sadness.

Personality
Cosmo is a kind and gentle character, though she often feels guilt because she was unable to save anyone from her home planet. She also seems to suffer from a low self-esteem issue, often calling herself "unworthy" or blaming herself for the hardships that she and her friends had to endure. Cosmo also dislikes violence, but acknowledges that fighting is sometimes a necessity, although she herself is unable to fight. Cosmo can be somewhat clumsy, but she is also quite resourceful; she also has a penchant of getting into trouble.

Cosmo shares similar qualities with Maria Robotnik and Tikal the Echidna each in turn. Both Maria and Tikal sacrificed themselves to save their friends/beliefs and are pacifists, but know how to fight when necessary.

Abilities and weaknesses
Cosmo does have a few abilities, being a plant herself, such as having the ability to empathize with plants, trees, or the planet and determine their state of life. Cosmo can jump high and gently float down with the aid of her skirt. She also appears to be able to unlock the power of a Planet Egg, as demonstrated in episode 58, where she caused the planet egg to activate and grow vines that entangled Dr. Eggman's mech, but also her friends and herself. When Cosmo is in her adult form, she is able to turn into a tree and weaken other planets.

Cosmo's weaknesses include being physically weak and acting a little clumsy. She has trouble carrying heavy objects but can use certain objects as defense. Cosmo also tends to get into trouble easily.

Family
The only confirmed members of Cosmo's family is her mother Hertia (Earthia in the English dub), who is the leader of the Green Planet council, and her older sister, Galaxina, who worries about Cosmo and her mother.

Hertia: Her mother, who is the leader of the Green Planet council. She decides to leave the planet when it becomes too dangerous, but is later killed after the Metarex board her refugee ship. In the dub version of Sonic X, she is instead known as Earthia. During Episode 78, she appears to Dark Oak--now returned to his form as Lucas--and speaks with him, telling him that thanks to Cosmo they now have 'another chance' together; however this dialogue appears only in the dubbed version. This has brought about suspicion that they were previously in love. It also brings the possibility that Cosmo's race will regenerate, though this is unlikely.

Galaxina: Her older sister, whom is shown to worry a great deal about Cosmo and their mother, Hertia. She is portrayed as very smart, sophisticated, and down-to-earth, the opposite of the dreamy Cosmo. She appears to perhaps be the eldest--or most authoritative--of the family who are shown in the beginning of Episode 77, while Cosmo is an 'infant'. She seems to look more like Hertia than the others. In the original Japanese version, she and the others on the ship had no official names in the show. In the original Japanese version, Galaxina has no name; she was referred to as one-sama ("big sister") by other members of her clan.

Seedling: Possibly Cosmo's child, a seed that was given to Tails by Sonic in episode 78, after Cosmo's death. It is yet unknown the name of this seed, or if it will survive. It could possibly be Cosmo herself, seeing as the seed it grew from is a white one, just as Cosmo had the Metarex codename, "White seed". Several fans venture to believe this to be a means of revival on her part. Alternatively, it could also simply be a part of Cosmo - all that Sonic could obtain. Plus, it could grow into just a regular plant (rather than a sentient one) as it is seen in the finale growing in a flower pot in Tails' workshop.

Cosmo is also friends with the crew of the Blue Typhoon.

Romance
Cosmo became good friends with Sonic and friends, but most particularly with Tails. The two of them ended up alone on a mission together at one point.Tails later protected Cosmo when Shadow targeted her for assassination. Cosmo's attractions to Tails were among the forces that provoked her to sacrifice herself to defeat Dark Oak, and her image appeared to him one last time after she was destroyed.