Perhaps a new villain in the story. Someone who has entered the town recently and has some sort of vendetta against Bella's family for reasons yet to be discovered. Another possibility could be a character who was jealous of Bella's dad's position in the community or his relationship with certain people.
One suspect could be a character who is secretly working for a larger, more menacing force. They might have targeted Bella's dad as part of a bigger plan. Or it could be someone who was misinformed about Bella's dad and thought he was a threat, so they took matters into their own hands and killed him.
It could be an old enemy of Bella's family. Maybe someone who had a grudge against her dad from his past.
She might be devastated. Bella could go into a state of shock initially. Then, she might feel a deep sense of loss and loneliness. She could also be filled with anger towards the cause of her father's death.
It could be an ex - boyfriend who was jealous and wanted revenge. Maybe he couldn't handle the break - up and decided to harm her in this extreme way.
A possible suspect could be an informant who has turned on Tony. Maybe the informant was promised a better deal by another party if they got rid of Tony. Also, it could be a new criminal on the scene who sees Tony as a threat. This new criminal might be trying to establish their power and reputation, and taking out a well - known NCIS agent like Tony would be a big statement. Another suspect could be a person with a grudge against the NCIS in general, and Tony just happens to be an easy target.
Perhaps it's an insider within the law enforcement or criminal justice system who has a vendetta against the BAU. Maybe they disagreed with the way Derek and his team operate and decided to take matters into their own hands. It could be someone who feels that the BAU has too much power and is trying to send a message.
One possible plotline could be Bella initially resenting Edward as her step - dad but then gradually coming to understand him better and they form a unique bond. Another could be Edward struggling with his new role and having to deal with his own feelings for Bella in a more platonic way than in the original story.
It could be an ex - lover. Maybe they had a bitter break - up and the ex - lover was filled with jealousy or revenge. Another suspect could be a business rival if Amy was involved in some sort of cut - throat business environment.
Obviously, Bella herself. And her partner, who could be someone she's in a committed relationship with. Her family members like her parents or siblings might also be important characters. They could be there to support her or add some family - related drama to the story.
Well, it could lead to all sorts of drama and emotional turmoil. Maybe Damon offers her comfort or protection.
Well, it could be a rival of Ciel's in business or in a social setting. Maybe someone who is jealous of his status or wealth and sees shooting him as a way to get ahead.
A rival law enforcement agency member could be a suspect. Maybe they see Deeks as a threat to their own investigations or operations and decide to take him out. It could be a power play within the world of law enforcement.