They're not actually sexy women with wings and little horns; that's just the form they usually use when someone summons them deliberately because it's the form most summoners want to see. They're malevolent, shape-shifting extra-dimensional entities, they're adept at emotional manipulation, they want to drain away a mortal's soul through physical contact, and they prefer having that contact given willingly. (Maybe the soul is more useful to them like that, or maybe it just tastes better.)

They don't need to seduce you. Maybe being a mercenary has severed your bonds to your family and your community? Maybe you've seen things that you wish you hadn't? Mommy understands. Mommy will make you all better. Give Mommy a hug...