Mystic Falls Historical Society Volunteer Day was an event in 2010, on March 5th. The Fell Family donated money, so Mystic Falls community could built a park. Carol Lockwood was the host of this event.
Stefan offered peace to Mason, which he seemed to accept with a handshake. But afterwards, he told Sheriff Forbes that Damon and Stefan are vampires. She didn't want to believe it, as Damon was one of her best friends and a member of the Founder's Council, but Mason told her he would prove to her that he was right. He put vervain in the lemonade for the volunteers. When Damon drank it, he naturally started choking, whispering "vervain" under his breath to alert Stefan of what was happening. Sheriff Forbes saw that the vervain affected him, and called in her duties for backup. Damon and Stefan assumed that Mason put vervain in lemonade to provoke him, and decided that they needed to take Mason out to protect themselves. They went to follow him in the woods when the Sheriff and her deputies shot them both multiple times with wooden bullets. Meanwhile, Caroline and Elena, who was pretending to fight with Stefan to assuage Katherine's demands, were talking when Caroline noticed her mother following Mason into the woods.
Caroline and Elena ran into Mason while they were following the Sheriff. Mason taunts Elena when she asks if he had seen Stefan, and threatens to out Caroline as a vampire to her mom as well. Caroline snarls at Mason, and he grabs Elena, putting her in a headlock, and tells Caroline to "be careful, necks snap really easy around here." Caroline states that she can take him, and punches him, and Elena runs away. Caroline kicks him in the stomach and Mason flew against a tree, allowing them to move on to the Lockwood cellar.
The Sheriff was interrogating Stefan and Damon about how many vampires are in town, and how they can walk around in the daylight. Damon pleads that he and Liz are friends, and she yells that their friendship was a lie and asks them the questions again. When they refuse to answer, they're shot again with wooden bullets. Caroline, outside the cellar, hears her tell the deputies to stake them both and to set fire to the bodies when they're done. When she tells Elena what is happening, Elena runs to go help them. Caroline tries to get her to stop, as she couldn't admit to her mother that she's a vampire. Elena went ahead and rushed inside, shouting at Sheriff Forbes to not hurt them. Caroline suddenly ran in a flash around the guards, shutting the cellar door and startling the her mom and the deputies, as she was moving so fast that they didn't know who it was at first. One of the deputies started shooting, and Caroline used the other as a shield against the bullets before biting and feeding on the shooter. She finally stopped, panting, and walks slowly out of the shadows, with her vampire face still present, and says hi to her mom. The Sheriff was shocked to realize her daughter was a vampire. Damon recovers by feeding on the dead deputies, while Elena helps Stefan relax and resist the blood in front of him, and they all debate on what to do. Sheriff Forbes pleads to Damon to just kill her, as she is so upset to find out that her daughter is a vampire. She even refused to look at or speak to her daughter, despite the fact that Caroline was refusing to allow Damon to kill her. Eventually, Damon says that he doesn't want to kill Sheriff Forbes, because they're friends, as he said before, and states that they will keep her in their cellar until the vervain is out of her system and then he will compel her to forget everything she learned that day. Sheriff Forbes ends up pretending to be sick, and instructs Damon to keep Caroline away from her. He argues that Caroline is her daughter, and she simply says "Not anymore." Damon, annoyed with her ignorance, tells her that she has no idea how wrong she is.
- This event happened in the Season Two episode Kill or Be Killed.
- In this event, Elena and Stefan have a fake fight.