Perhaps Sonic himself could be seen as a sort of antagonist in this situation. Even though he's yelling at Tails, it could be that his own short - tempered nature and lack of communication are the real problems. Tails may not have done anything truly wrong, but Sonic's reaction makes it seem like he has.
Another possibility is a new character. This new character could be causing trouble between Sonic and Tails. For instance, the new character might be spreading false rumors about Tails, which makes Sonic angry at Tails.
One possible plot could be that Sonic yells at Tails because Tails made a risky decision during a mission that almost put them both in danger. For example, Tails might have tried to take on a powerful enemy alone without waiting for Sonic's backup.
The main antagonist could be the Avengers' own bureaucracy or leadership structure. Peter might be yelling at them because their rules and decision - making processes are preventing them from doing the right thing. He might see this as a hindrance to their ability to protect the world effectively and is frustrated enough to yell at them to try and bring about change.
It could be Dr. Eggman. Maybe he has sent some of his robots to the area where Sonic and Tails first meet. The robots are causing chaos and Sonic and Tails have to team up to stop them, which is how they start to bond.
Dr. Eggman could still be the main antagonist. Even if Tails turns evil, Eggman might see him as a threat to his own evil plans. He could try to stop Tails while also taking advantage of the chaos Tails is causing among Sonic and his friends.
Sonic is often paired with Tails. Their friendship in other Sonic canons carries over, and in Sonic Underground fanfiction, they might have new adventures together. Sonic's speed and Tails' smarts make them a great team.
Most likely Sonic and Tails would be main characters. Since it has 'tails raised' in the title, Tails is clearly important. And Sonic is often the central figure in Sonic - related fanfictions.
No. Most Sonic fanfiction focuses on positive relationships and adventures. Killing off a main character like Sonic in such a way is not very common.
A rogue robotic entity could be the main antagonist. This entity has the ability to roboticize other beings and views Tails as a prime target. It wants to use Tails' body as a vessel to spread its robotic influence further, so it sets out to roboticize him and then use him as a tool for its own dark purposes.
Dr. Eggman could be a likely main antagonist. He might use his cunning and various inventions to manipulate the situation and make it seem like Tails or Rouge are traitors in order to further his own evil plans, like taking over the world or stealing some valuable chaos emeralds.
There could be many potential authors. It might be a fan who is really into the relationship dynamic between Bruce and Dick. They could be someone who has been following the comics or other media where these characters appear for a long time.