[After doing a little more discreet digging] It seems he's ultimately obsessed with a man called Bruce Wayne/Batman though he seems the type to view anyone who gets in his way as an acceptable casualty. I've also been told that putting a bullet in him might not work like it should.
[And more digging for a few minutes]
They seem to though I am unsure of how serious it is or if it's just a friendship.
But Banner has asked if we could keep an eye on Stark while Stark is in the hospital in case this Ra's tries anything to Stark.