Sonic the Hedgehog

Sonic the Hedgehog, is the main protagonist of Sonic Freedom Forever. He is an anthropomorphic hedgehog born with the ability to run faster than the speed of sound, hence his name, and possesses lightning fast reflexes to match. As his species implies, Sonic can also roll up into a concussive ball, primarily to attack enemies.

Past
Sonic was born on South Island by his father, Paulie, an air mail pilot, and his mother, Brenda, an explorer adventurer. When Sonic was a toddler they noticed how Sonic can move extremely fast when running and they were never quite sure how Sonic gained such a power, it was theorised by doctors that it was a hidden genetic gene that Sonic had inherted, but whatever the case, Sonic's parents loved him. Even when Sonic was a kid he loved to eat chili dogs and would run about everywhere like the happy child he was, and occasionally Sonic would ride in his father's plane along with his mother while Paulie flew the plane, and they would all travel together to some place with Brenda guiding them to adventuring.

However, tragedy stuck when Sonic was only 8-years-old, Paulie and Brenda had to go together for an urgent business trip and Sonic's uncle, Charles (or as Sonic teasingly preferred to call him as "Uncle Chuck"), was tasked to look after Sonic for a couple of days until they came back, unfortunately this was the last time Sonic would ever see his parents alive. A couple of days soon became several weeks and Charles became increasingly concerned for why they haven't contacted since. Eventually someone did come to the door to give answers, unfortunately it was all bad news, Paulie and Brenda were both killed in a freak plane accident, possibly caused by some kind of engine malfunction, causing them to crash to their demise. Charles had to tell Sonic the grave news and once he did, it bought Sonic into tears and it broke his heart. Charles was deeply sadden by the news as well but he reassured Sonic and promised he will look after him like if Sonic was his own child.

Afterwards, they learned that Sonic had inhered his father's other plane, the Tornado. This one was his father's favourite plane and it had the word Sonic labelled on both sides of the plane, more so because of his father's fascination of Sonic Booms. Sonic cherished as a reminder of them.

Fiona Fox
Fiona Fox is Sonic's girlfriend. Sonic first met Fiona in the town of Green Hill Zone, Fiona was on the search for her long lost parents and when she had the bad news that they didn't live at an old address anymore, it bought her to tears and then Sonic noticed her, and it was like how Sonic felt when he lost his parents and he didn't like anyone being upset. Sonic came to cheer her up and Fiona felt better, but just then the town is suddenly invaded by Dr. Eggman and his horde of robotic badniks. Sonic and Fiona agreed to fight back, and they successful defeat Dr. Eggman.

Miles "Tails" Prower
Tails is Sonic's best friend and sidekick, the two are as close as brothers and always stick by each other's side.

Tangle the Lemur
Sonic and Tangle the Lemur have been described as "kindred spirits" due to having similar traits to each other, namely their skill and enjoyment in battling Badniks, as well as the confidence they share in doing so. Even after meeting for the first time, the two were able to synchronize with each other in their battle against multiple Badniks. Although their personalities seem to differ slightly, their enjoyment in fighting is something that they share together.

Dr. Eggman
Dr. Eggman is Sonic's arch-enemy and nemesis. Sonic first encountered him on the very same day he met Fiona in Green Hill Zone as he attempted to demolish the entire town with a wreaking ball to then construct another badnik factory, only for Eggman to then fail after being beat by Sonic and Fiona. Because of Sonic's hatred of anything unjust, he holds a great mutual loathing for the doctor and his evil plans to take over the world.

Trivia

 * Sonic and Fiona for a brief time were a couple in the Archie Sonic comics, until she betrayed the Freedom Fighters and became Scourge the Hedgehog's girlfriend.