Some months ago, way before she became good again.
Fiona and the Anti Freedom Fighters/Suppression Squad were attempting to steal millions dollars from a bank near the Acorn Kingdom.
But things turned a bit sour.
Fiona watches Scourge as he kills a defenseless bank manager with its own two hands causing the people of the bank to become afraid.
She nearly feels bad for him.
Fiona tries to get the money from the vault but it was locked. It needed the code and only the bank manager knew it.
Yelling at her boyfriend from killing the bank manager for being so careless. Scourge was about to argue with her back but more teams of guards showed up.
As Scourge and his crew fights off the remaining armed guards, Fiona tries to find a way inside the vault until Sonic and the Freedom Fighters arrive.
Scourge calls out a full retreat and flees in a getaway car, leaving Fiona to distract her former friends. Scourge assures his girlfriend that he'll break her out of No Zone Prison when the time comes.
She is then taken for interrogation by Princess Sally Acorn, where she refuses to give up any information.
So Sally asks her father to sentence the fox to life in prison, but Fiona insists she'll be freed within the day.
Fiona then spends six months in prison waiting for the green hedgehog, while Tails, her visitor trying to convince her that Scourge doesn't care for her. But she refused not to listen to him as she had before since the day that she betrayed him.
After three more months, Fiona somehow managed to get out of prison. She fully understood now that her boyfriend wasn't coming for her so she decided to escape all by herself once more.
One week later, while hiding from the authorities she was kidnapped by a male mobian raccoon who works for Dr. Eggman.
He simply knocked her out over the head and took her.
Afterward, Fiona awoke and founds herself trap inside a glass ball suspended over thousands of meters below ground that could kill her. But she wasn't the only one trapped in a glass ball.
Sonic as well. He arrives at the scene to fight his nemesis only to be caught.
Not until a minute the two tailed fox and the green hedgehog also come to the scene. They were forced to work together if they're going to get their friends back.
Dr. Eggman demands Scourge to choose one to live and one to die. Surprisingly, the evil hedgehog chose to save Sonic to deny Eggman the satisfaction of killing him, prompting Sonic to chase after him.
Fiona was about to be crushed as she was getting closer below the ground. That is until Tails flew down to save her from and carefully landed.
Fiona finally realizes for all this time that the green evil maniac never really cared or loved her from the beginning. She deeply apologizes to Tails for being a fool and a selfish absolute jerk from not listening to him.
He was right and she was wrong. She told him nothing like that would ever happen again which, he immediately believes her.
For all the things she did and all the sins that she committed. She vows to never be the green hedgehog's girlfriend ever again.
She eventually became Tails' girlfriend regardless of his age and made a promise to him that she will never betray him or her friends again.
Few days later.
Tails offered to Fiona to rebond with the Freedom Fighters. Her crimes could be forgiven, she doesn't go back to prison. Naturally the others on the hand won't forgive her for pulling such a cruel betrayal on them. There's no help in it though but that's all in the past.
It no longer matters to her but the past always matters.
Tempting offer, however she refuses to come back and decides to become a vigilante upholding the law.
Her new boyfriend didn't like the idea at first but he decided to give his full support to her in secret.
Fiona traveled to Anti-Mobius. She arrived at Scourge's castle to break up with him. Not after she teaches him a lesson for abandoning her and his goons.
Fiona fought them all off without getting a scratch on her and destroyed the castle, leaving her ex boyfriend in a pile of rubble at her mercy. He asked if she was going to kill him but she spared him, she didn't want to get her hands dirty yet.
Fiona then leaves to return to Mobius where she now begins her vigilante role to pretend to both the innocent and her ex friends whether they want her help or not.
