How can I come up with story ideas?

I'm a huge fan of the Mortal Kombat franchise and I love the lore in it. I want to come up with my own fanfiction. I'm trying to come up with some stories that take place in a timeline of their own. The first two stories might have plots similar to the first three games, story one will be similar to the first MK game and story two might be similar to the second game or the second and third game. I just can't come up with stories or subplots at all. Any tips on coming up with stories?