Why do the Foresworn attack me all the time? They act like bandits, 'attack on sight' is their policy. Why? I have never did anything to provoke them.

It's getting annoying now. I want to go in the mine that has lots of gold in it but it's crawling with them. Lots of times I haven't been able to fast travel because they keep popping up. What's their problem? I helped Madanagh escape cidhne mine, you would think they would be grateful.

Seriously, what's their problem?

A good question. The lore says nothing about their hostility towards everyone. In my eyes they're just a bunch of bandits.

But perhaps someone here has deeper insights?

If your not a Forsworn, you an enemy of the Forsworn. Thats why they attack you on sight.

Yeah, they shouldn't attack you, unless you attack their first or invade their fortress.
And they should be friendly after you release their king...

I hate to kill their with my Breton, since they are half Breton too.
And I really see them as some kinda of "4th era Orcs", without a country and stuff....

They have nice tattos and clothes too! They could make a fortune with that...and selling their own heart to people...

why do forsworn briarheats have their heats cut out and replaced with briars? What are briars anyway?

A Briar Heart is stitched into the body of a dead Forsworn by a Hagravan during a ritual conducted to reanimate them. Forsworn revere Hagravans, so they're apparently chill with it.

By freeing their king means you are with them, so why after that they continue to attack us?

Because bethesda the greater gods, those above the nine eight divines, have decided to ignore this possibility because there were not enough time/money to make a new quest

Try wearing the armor of the old gods? I ran in to two different forswarn camps escaping Markath after the prison break and they didnt bother me with that armor on.