I've got a bit of difficulty in coming up with the subplot for my novel. The theme is Justice, preferably something to do with war crimes. If anyone is familiar with Lois McMaster Bujold's Chalion series, it's a fanfiction on that - gods, curses, horses, sabres and Roknari enemies with unusual ideas about marriage, succession, and a knee-jerk reaction against anything out of the natural order, including and especially homosexuals, demons, and bastards. Anyone got any ideas?
I think the best way to look at this is to ask yourself: How would this be a challenge to your character? Would s/he feel misanthropic about all the unusual things, or are they a character who goes along with the rules? Would something, someone, or an event cause them to change their mind about some of the issues?
Have a beginning, have an end, then just have fun writing the in between bits! Find your favourite story and plot the action/plot point structure against yours, find things you like and things you don't, do a bit of research, find elements you wanna work in, make a beat sheet or outline, change it if you want, nothing's set in stone, and just have fun. Don't make it like work, otherwise it'd way less likely to come out the way you want it. If you're unsure about something, leave it until review.