Use Gray... Black sucks when reading. and use an option where the user can choose between light or dark.
Why did you even join up a service where you had to make a 1 year commitment with no option of switching? Why not ask for advice from your friendly armchair engineers? Baka nano?
Dark theme is best for reading at night... most people read novels at night let's do the math... 1+1=3 Blood theme it is
Can you use plugins Lys-chan? You can use an Acessibility plugin to create a dark theme, and leave the default as light one. It's what I do on my site at least.