How do you feel about AUs? (Since you clearly like Marvel!) xavier_institute is an AU that isn't based on any specific version of the Marvelverse, but focuses on the X-Men and the students at Xavier's school. There's an ongoing plot and regular missions, with daily school life in between. We're at a pretty comfy size, where new posts come in most days, but not at such a rate that you can't peace out for a week and be totally lost when you try to catch up again.