Harpy
A long time ago I had an outline for a post-apocalyptic OD&D game called Black City (Though I've since changed the name to Demon City, because I learned some other OSR thing had the name Black City). In it there were two main forms of progression: cyberization and demonization. Demonizing involves courting the 25 monsters of the City: either through bonding or integration. Once bonded, the monster can be called upon. Each has specific tasks they excel at. To summon them, score 8+ on a reaction check. The basic idea is similar to Luke Gearing's idea here. In other words, each monster is effectively its own spell. Integration is straightforward: take on specified physical qualities of the monster in question.
Here's a monster entry:
Harpy
3HD / AC as Leather / Damage d6+2 / Fly as fast as wind / Stunned by ugly music (Save vs. Death)
Beauteous winged women with viscous taloned feet; spring flowers and lost hopes dash free in desert wind, a memory.
They nest contemptuously above the scraps of mankind and gossip insatiably about the love lives of chieftains; the strange wares of traveling peddlers; washerwomen and their private anguishes. The wind carries stories up from villages and bunkers, their ears tuned to hear even whispers. The rhythms of life, so hard for mankind, play out like a symphony. Man’s cruel imitation of natural music drives horror through their sensitive hearts.
They alight only to take. Careful of the dinner spread: don’t be careless. And careful of the young village boys who the Harpies will happily take and raise as servants and gigolos—forced to provide seed for their infernal spawn and guard their nests with spears of human bone.
Yet in spite of their mischief men still fall in love with the Harpies, even over their own wives: fall under their spell at your leisure and no others will compare. The lovers of Harpies desperately attempt to fulfill unspoken mandates: with an eagerness bordering mania they foist favours and gifts upon the winged women. Earn a kiss to break the spell, but a portion remains. Any man who has conquered alien affections is rendered immune forevermore to demonic mind control and mental manipulations.
BOND: Harpies can be placated with rumours and gossip—performance is important, exaggeration expected. Stories of betrayal and impossible longing rank highly—especially if they involve the tattered bourgeois. But not a word of violence; a Harpy would sooner scratch out your eyes than hear a hint of vulgarity.
Call upon aid for the following:
- Theft
- Messages
- Eavesdropping
- Rumour spreading
They demand fine treatment. Disposition is modified by the following, to a max of +4. They begin with a disposition of +1:
- +2 for wooing a woman the Harpy approves of.
- +1 for a gift of jewelry worth at least 1000cr.
- +1 for forsaking violence, and sticking to it.
The murder of innocents, gratuitous violence, or fights without just cause in their presence cause a -1 in disposition.
INTEGRATE: A supreme loverboy may court himself a Harpy, should he avoid her spell and show her a world of satiety and excitement. Take her to a masked ball; let her be the star of the stories she covets so. Then make love till both are one: the loverboy grows wings, flies freely, and may listen to the wind like a Harpy.