Just write whatever story you want, wherever you think of it. As a starting point for practicing writing, I write about 1,000 words every day. I hope I can tell this story well. What I am probably thinking about is a person who will not die, and a series of stories that happen to him and around him. Is immortality a blessing or a curse? As time goes by, everything around him is changing. Only he is fixed at one point in time. What does that mean to him?
This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.