One possible plot could be that Lauren is in a state of shock after being hit by the truck. Her friends in the 'Lost Girl' world then rush to her aid. They might use their supernatural powers to try and heal her or at least keep her alive until proper medical help arrives. There could be a lot of emotional turmoil as they fear losing her.
Kenzi would be an important character too. She's Lauren's friend and has a big heart. She'd probably be the one running around trying to get all the necessary supplies or information. She could also be the comic relief in the otherwise tense situation, but still be deeply concerned about Lauren's well - being.
In the fanfic, the 'gets hit and sees red' situation might be a turning point. For example, if she was previously a meek character, this event could be the catalyst for her to stand up against oppression. Maybe she was hit by a bully or an antagonist, and seeing red means she's now ready to fight back, whether through physical means or by using her wits to outmaneuver her opponents.
The consequences can be very severe. She could suffer from serious physical injuries like broken bones, internal bleeding, or even head trauma which might lead to long - term disabilities. There would also be emotional trauma, such as developing fear of going out, nightmares, and post - traumatic stress disorder. Financially, her family may face huge medical bills for her treatment.
Perhaps she starts to question the safety of her environment or the people around her. This could make her more cautious and observant, leading to her uncovering secrets or plots that were previously hidden. For example, she might realize that there are those who wish her harm and start to take steps to protect herself and those she cares about.
Sebastian, being the efficient butler, would likely immediately take charge of the situation. He would ensure the girl gets proper medical attention if possible. He might also start investigating the circumstances around the accident, suspecting foul play as is often the case in the 'Black Butler' world.
Well, he might find that the love story takes a very strange turn. Maybe the girl he loves in the present time is somehow related to the accident in the past. For example, her ancestor could be a witness or even the driver of the car that hit him. And this discovery could either strengthen their bond or create a huge rift between them depending on how they handle this new information.
Kick - Ass himself is an obvious choice. Their partnership in the original works was great, and in fanfiction, it can be explored further, like how they develop a deeper friendship or face challenges that test their alliance.
There's no way to determine who the girl was without more details. She could be a local from a lakeside town or a tourist visiting a beach area. It really depends on the context of the particular story.