So the other day I finally decided to do it. I hadn't done the FC quest so that I sided with Madanach yet so I went ahead and made a forsworn. It has been quite fun and I found some strange things out. I used the console to add forsworn faction to Lydia, who I was reluctantly letting follow me just so I could level illusion. I did so also with Delphine and Esbern so I could get thru karthspire without a fight, and we did end up fighting the dragon alongise the forsworn.

So then I decided to go all the way with Lydia as a Forsworn. I gave her forsworn gear, including two axes, deleted her default stuff and now she looks the part. I also gave her dual flurry, which is working i think because she dual wields now like a freakazoid. I never seemed to have any luck addign perks to npc's before. I also setscale her to default breton height. This was all pretty fun, then it got even better. she just started yelling forsworn battle cries which was pretty cool. And finally, for some reason my character waited until she was in Skuldafn and she started yelling forsworn battle cries. I was amazed. Never heard the main character speak outside of shouts before. I don't know why it waited that long though as she was forsworn faction since minute one of playing. Anyway, I suggest that any PC remotely curious give it a try as it is a pretty cool excuse for making a character and it removes all those pesky decisions about what to equip and which smithing perks to take....

Wait...

So, you added PC to Forsworn faction?

yeah, like right off the bat. rp is she was caught as a forsworn and got death penalty. i then made her run straight toward markarth and the closest forsworn locale I could find and used the console to add what equipment i could not find, smithed it out and proceeded straight to markarth to do the forsworn conspiracy as well as i could from a forsworn perspective.

I really hope there's a faction pack of sorts, that fleshes out the forsworn stories.
They need to be an entire guild line of quests.