This plot would require us to double, but I don't think you'd mind. Would you mind playing a vampire? :p
So there are two step brothers. In this world, magic is known of but rare. They both come from really established bloodlines and are both harboring great potential. When they were younger, they lived on an estate with their parents, but my character loses control of his power one day and accidentally hurts yours. Nothing too bad, but he is sent away to live with their eccentric uncle, who teaches him to control his powers with the help of a familiar. His familiar is captured in a book called a grimoire, and can be whatever creature or spirit you want him to be, but he has to be able to appear human.
Anyways, the two brothers eventually lose contact. One day, your character is attacked at night by a vampire, and if turned into a vampire himself. These vampires can compose themselves, and do not sparkle, lol. They also age, and are sensitive to the sun. Also, they drink blood otherwise they eventually starve to death. We can make up more lore as we go along, bit it will have a more fantasy feel, while this RP is a bit more SciFi. Your character is sent to live with the uncle as well, because being a vampire amplified his magical ability. My character is tasked with training his brother. I will control the vampire that bit yours, which will be a recurring character, as well as the brother. You will control the grimoire, though I suppose you can substitute it with another role. I was thinking we could have he uncle house a bunch of teenage boys with little self control so that will give us a lot of ways to ship?