One of my favourite bits of lore in Warhammer 40k is that of the Aeldari Goddess Isha and Nurgle.
Isha is the Goddess of beauty, fertility, healing and harvest. When the Chaos God Slaanesh was born, it ripped most of the souls of the Aeldari from their bodies and consumed them. It was then powerful enough to fight, kill and consume Asuryan, the Phoenix King (King of the Aeldari Gods), as well as Vaul the God of the Forge, Kuranos the God of the Hunt and whomever else.
Isha would have been a great prize for the Lord of Excess to violate, kill and consume but he was fought off by the ponderous and ancient might of Nurgle.
Nurgle won and stole away the Goddess and she was then imprisoned near his cauldron where he creates all of his new plagues, poxes, viruses, etc. Because she is the Goddess of Healing, she can be experimented on over and over and she would then recover from the diseases, giving Nurgle a healthy blank slate to work off of over and over.
It has been suggested that Isha now willingly resides with Nurgle. This is because outside Nurgle's protection, she would likely be killed and because in THIS position, she can send forth inspiration and dreams to the healers of the galaxy to combat the diseases that Nurgle infects her with.
Even in this grimdark setting, this has led fans to make some hilarious art and suppositions that basically there unlikely allies have a lot in common and that it is a pairing that is sort of like a relationship.
Happy postulating THAT situation!
Stay healthy!
