Diadem of the Bitch
A magic headband that activates when placed on the head of a human corpse. It animates the corpse as an undead, preserves the corpse and possesses it with the soul of a hellhound.
The animated corpse's eyes (or sockets) glow with infernal red flame.
She understands common and infernal. She has skills suitable to hiding, stalking and skulking.
The hellhound prefers corpses that are female, pretty and fresh. She will need help to remove her from her current body and place her on the prospective new body.
As the animated body is undead she can be neutralized by turning and takes damage from holy water, but she does not need to eat, drink or breath.
She is not especially smart and she often fails to spot changes in the social mood around her.
By inflicting permanent damage to the body she can increase her speed and agility for a short time allowing her to run and jump.
She can also use her hellhound's fiery breath weapon. Though it will also damage her body.
Such injuries cannot be healed and are accompanied by the smell of cooked pork.
Vastly less dangerous then the Diadem of the Slut or the Diadem of the Lady as it lacks the telepathy, high intelligence and spell-like abilities of those items.
"Is that corpse your sister? Wow, that sucks. Can you put me on her? She's cute."
Now the Diadem of the Bitch requires a willing associate, but she lacks the tools to securely entrap one. This normally puts her into a servile role.
Not that she wouldn't happily murder your childhood friend for her body, but she has been around the block enough times to know that doesn't always go her way.
So she will usually ask first.
She tends to relax and enjoy her time when she finds an associate who values her sexually. This normally results in her taking a partnership or sometimes even master role.
So she will make the availability of her cold dead body known.
She is afraid of being lost once more in the dirt at the roadside or in a chest forgotten for decades.
Now in a porn game... This results in a lot of corpse fucking. A lot of fresh new faces with that familiar grin.
The occasional suspicious "I just happened to find this girl here, who has been conveniently stabbed to death, so could you put me on her? I'll suck your dick and stuff."
I assume the middle is about evading the attention of a holy order out to stop your rampage of infernal corpse romance.
The end would be a standoff with a superior Diadem.