(more advanced written than my other post)
*Golden Winged Knights*
rapport + hornet ring + max souls gain.
(shield of want x2, symbol of avarice, silver serpent ring) and slumbering dragoncrest ring.
will allow you to sneak up on them turn them friendly and backstab them without problem.
on NG12 you get around 100K per kill with this tactic.
(keep in mind if rapport would stop be active they will attack you.)
(so after you've backstabbed one, recast rapport just in case.)
(Dagger might be your best weapon for this, depends on your build)