This is the problem with having full origin stories in the group stories. It holds everything else up while we're waiting for it to be finished. Best to just start in with the group and fill in the backstory in bits and pieces later on when it actually fits with the flow of the story.
I think it's actually more interesting to read to see a character who is strange enough or otherwise interesting enough to warrant a backstory but have to guess at it for awhile before it's revealed, a la Lost. And again, it doesn't slow the pace of the main plot.
