Don't read if you don't want spoilers re: endgame -

So I have a friendly angel in the fort... it's an archangel according to the ascii art. It came out of one of the pockets uncovered by mining near an adamantine vein in an obsidian spire. The units menu just says it's a resident, I had all my marksdwarves set up nearby and then they refused to shoot it which made me panic for a minute, everything that's come out of the area so far has been hostile!

This seems sort of unintended? Has anyone else experienced this? I thought they were supposed to all be hostile... I'm not sure if I should kill it or not. So far it hasn't generated any reaction in dwarves, positive or negative, which is weird; apparently a giant angelic guardian beast isn't noteworthy enough to replace thoughts about the weather.