Sonic the HedgehogThe main hero, and POV character, of the story. With the capabilities of running at just over the speed of sound, he's the world's fastest hedgehog. Though a tad short-tempered, he is always willing to help anyone in need. Above all else, he values freedom and life judged by his own rules.
- Always Accurate Attack: The Homing Attack.
- Amazing Technicolor Hair: As always, he has blue fur and quills.
- Baleful Polymorph: His initial transformation into the Deku Scrub form, courtesy of the Skull Kid's powers.
- Body Horror / Transformation Trauma: His initial transformation into the Deku Scrub form.
- Kid Hero: He's fifteen years old.
- Mode Lock: The Deku Scrub form, forced by the Skull Kid until he re-acquired the Mystic Melody.
- Nice Guy: He's this; a huge contrast with the significantly more acerbic Tatl, as shown by his calmly asking Alfred for the Bombers' password instead of shouting and bullying him.
- Species Surname: His last name is "Hedgehog."
- Spin Attack: His Spin Dash attack.
- Super Speed =/= Super Reflexes: His specialty.
Tatl BerylliaThe main heroine of the story, and the oldest of the Beryllia kids. Left behind and injured by the Skull Kid, she was forced to team up with Sonic in order to stand a chance at getting back to her younger brother, Tael. An overbearing learning fairy, she is always thinking of her younger brother, worried for his safety at the hands of the Skull Kid.
- Aloof Ally: Initially, she only joined Sonic because the Skull Kid abandoned and (indirectly) injured her. In fact, as shown by her letting Sonic fall in the Subterranean Forest, she makes it clear that she couldn't care less about his safety.
- Amazing Technicolor Hair: She has white hair with a yellowish outline.
- Anti Heroine: Due to her arrogant and condescending attitude.
- Combat Pragmatist: She isn't above using blunt objects and cheap tricks to get what she wants.
- Deadpan Snarker
- Fairy Companion: After being separated from her brother and the Skull Kid, and injuring herself in the process, she was forced to work with Sonic until they can find them.
- Fairy Sexy
- Good Is Not Nice: Though she generally means well, she can be quite a jerk at times.
- Jerk with a Heart of Gold
- Kid Hero: She's fifteen years old.
- Punny Name: Her brother's name is Tael. Put the two together and you get Tattle-tale, as Sonic himself mocked after she made fun of his name:Sonic: The same one who'd name their kids Tattletale?
- Tsundere: A Type A example with Sonic, she regularly switches between belittling and snarking at him, and being surprisingly cool with him, to the point of lightly flirting with him at times.
- Winged Humanoid
Tael BerylliaThe youngest of the Beryllia siblings. A somewhat repressed learning fairy, he was forced to stick with Skull Kid while his sister was trapped in the Subterranean Forest. He reluctantly follows the imp around everywhere he goes, despite the physical abuse he takes from him.
- Amazing Technicolor Hair: He has purple hair with a reddish outline.
- Dark Is Not Evil: Despite his dark-purple appearance, he's one of the nicest characters Sonic runs into in Termina.
- Kid Hero: He's eleven years old.
- Non-Action Guy
- Shrinking Violet
- Winged Humanoid
The Skull KidA forest imp in the possession of a mystical mask. Hidden within that mask was tremendous power - a power that not even he understood. He is now the immediate threat to the welfare of Termina.
- Big Bad
- Everyone Calls Him "Barkeep": Even to his close friends, he is only known by the title of Skull Kid.
- The Heavy: Everything that occurs in the story can be linked back to him in some way or form.
- Mask Power: His mask gives him the power, among other things, change people's bodies into different shapes and forms.
- Troll: Even before he acquired the mask, his talent was basically pissing people off for laughs, hence why his only two friends are Tatl and Tael.
Lady Venus BerylliaKnown by her title of the Great Fairy of Magic, she's the kinda-sorta mother figure/mentor for Tatl and Tael, as well as being the leader of all fairies in Termina.
- Amazing Technicolor Hair
- Heart Trauma: She suffered this from the Skull Kid's attack on her.
- The High Queen: She serves as the queen of all fairies.
- Older Than They Look: According to Tatl, despite appearing to be in the human equivalent of her late twenties, she is actually over five hundred years old.
- Winged Humanoid