With my previous post you could think I don’t like The Ruins of Undermountain but that’s not the case, there’s a lot of clever stuff in its pages.

One location/encounter in particular reminded me how much I like unlikely allies as a DM. I’m not talking about factions (which are nice too) but monsters or seemingly evil characters that, under certain circumstances, can bond with the PCs. I like it but I also know from experience that Players are absolutely thrilled by it!
But here’s the one I’m talking about here (1991’s spoiler I guess):
This vampyre was once a female human merchant of Waterdeep, Spadreera Omarkhont. She now appears as a slim, svelte, beautiful (but dirty) creature clad only in ash-covered tatters, her eyes glittering with red fire and much of her hair all burnt away.
Yeah, she’s a fire vampire.
Spadreera is lonely, more than anything else. She’d like to chat and gossip about Waterdeep regularly, with someone she could regard as a friend and will try to befriend any beings who survive her initial attack, and cease hostilities when she offers to. PCs who befriend Spadreera never need fear attack from her again. She will not accompany PCs out of the dungeon, and is reluctant even to leave her lair but she will meet PCs at agreed-upon places elsewhere on this level, and even aid them against encountered monsters. She does not appreciate being used, however PCs would be wise not to try to dupe her into fighting every other monster on this level. Spadreera will plead to any befriended creatures for visits as often as possible! In return, she can guard treasure for PCs, give them all the (sadly outdated) information she knows about the intrigues and secrets of Waterdeep, and give them advice on trade (she was a very shrewd merchant). Her lair can become a hideout and safe house for PCs, if they conduct themselves in the right manner.
She’s still a monster in some way but:
Spadreera’s alignment and tendencies are overruled by her loneliness; she will look for prey and opportunities to unleash her cruelty elsewhere, among the monsters that roam this level, and never harm PC friends. She will even nurse injured PCs faithfully back to health without attacking them!
What an interesting NPC!
Do you know of any other cool unlikely ally?