Perhaps a mysterious stranger who has some unknown vendetta against the Heartland family. This person could have been lurking around the ranch for a while, waiting for the perfect opportunity to strike. Or it could be someone within the community who has a hidden agenda and sees Amy as an obstacle to their plans.
There may be. There are fanfic communities that strive to create content suitable for a wide range of audiences. In the case of an 'eren gets mikasa pregnant fanfic', it could be written with themes like family values, the growth of their relationship, and the anticipation of new life. For example, it could detail how Mikasa's character might change as she prepares to be a mother, and how Eren steps up to support her, all while keeping the story appropriate for all ages.
One great Levi x Eren one - shot fanfiction is 'The Unspoken Bond'. It delves deep into their complex relationship. The author beautifully portrays how Levi's tough exterior softens in Eren's presence. Another one is 'Midnight Encounters' which has a lot of intense emotional exchanges between the two characters. It shows how they rely on each other in the midst of the chaos of the Titan - filled world.
Maybe it's a human who has somehow discovered the world of demigods and is afraid of their existence. They shoot Annabeth out of fear and misunderstanding. Another option is that it's a rogue demigod who has gone bad and is working against their own kind. This character could have a personal grudge against Annabeth specifically, perhaps because of her intelligence and leadership skills which they envy.
Unfortunately, I don't have information on the author of this particular fanfic. It could be an amateur writer who just wanted to explore this scenario with the character Ciel. There are numerous fanfic communities where such works are published, but without more details, it's impossible to say who wrote it.
Well, without reading it specifically, it could be about a character named Ciel getting a shot. Maybe it's a medical shot in a hospital setting and the story focuses on Ciel's fear or bravery during the process.