Sometimes Slaanesh would knock on Nurgle's door and stare at him with a teasing look, as if asking whether he had done this and that to Isha, or this and that again.
Slaanesh's appearance disgusted Nurgle. Debauchery was not his way. He roughly drove Slaanesh out, and Slaanesh wailed that Isha was, in a sense, also her mother; she merely wanted some milk to drink.
This reminded Nurgle of something. Milk was an excellent substance for fermentation. So Nurgle asked Isha for some milk to make drinks such as yogurt, and Isha, grateful that Nurgle had driven Slaanesh away, gave him a little.
After all, the Aeldari no longer needed so much milk to raise their young...
Having obtained the milk, countless inspirations surged through Nurgle's mind. He first poured out a little to taste it, then, finding it bland and flavorless, began to improvise freely.
Nurgle buried himself in his work and brewed an indescribable horror. He wiped the sweat from his brow and gently fanned the scent toward his nostrils with his palm. The sour aroma was rather appetizing.
Nurgle had no intention of keeping this thing to himself. Since it had been made from Isha's milk, he felt that her children ought to get a share.
Naturally, Slaanesh could have a taste as well. Without her reminder, Nurgle would never have thought to make such a thing.
The smell of the yogurt also drew Isha's attention. Standing beside the great pot, she rose onto her toes and peered inside. The horror within turned her little face pale, making her realize that, out of gratitude, she had done something exceedingly foolish.
This toxin-filled yogurt became an excellent poison made exclusively for the Aeldari. If it were scattered across the mortal realm, the Aeldari, already devastated by Slaanesh, would