Isha

One of the many Eldar gods, Isha's domain is healing, fertility, and the harvest. She is one of the few genuinely nice Warp-entities in Warhammer 40,000.

So, naturally, grimdark things happen to her. A lot. To give some sense of scale, the story behind Eldar's spirit-stones is that they are Isha's tears. Seeing as there were once trillions of Eldar, and enough spirit-stones for all of them, Isha has been crying quite a bit.

The only good thing to happen to Isha is that, when Slaanesh was born, Nurgle protected Isha from getting eaten like the other Eldar gods; apparently, he was smitten with her. He shows his love by force-feeding her his new diseases, sending the ones which cause the most interesting reactions out into the galaxy. Isha makes the most of her predicament by healing herself, and whispering the cure to the galaxy.

In /tg/ canon, the Emperasque recently rescued her from Nurgle's garden; he claims he only did it because he needed leverage over the Eldar, but he's also apparently a much nicer guy after ten thousand years of forced introspection.