I think it's a bit of a fine line really. You don't want long time readers skipping paragraphs cause they are basically copy/pasted from previous books (I have actually read published series that did that and I often found myself skipping several paragraphs at a time). You want to give enough that new readers get the basic gist and hopefully interest them enough go looking for more, while not boring someone who's read everything previous.
I think the fact it's a fanfiction crossover makes it a bit harder. You'll get people who'll be reading one of the stories cause it's crossed into their fandom so they'll want to start there and may not have an initial interest in reading more then the one story so you need to introduce the protagonist to them.
All that said, I'm an amateur reader and this is just my 2 cents.
I think the fact it's a fanfiction crossover makes it a bit harder. You'll get people who'll be reading one of the stories cause it's crossed into their fandom so they'll want to start there and may not have an initial interest in reading more then the one story so you need to introduce the protagonist to them.
All that said, I'm an amateur reader and this is just my 2 cents.