Thank you to Dexilo1 for the suggestion - apologies it took so long.

"You seem surprised, Paul," Lady Jessica gave a flicker of a smile.

Paul had fallen backwards, even his honed prana-bindu training thrown off by the protrusion of the base of his spine, as a hairless pink tail flopped onto the hot sand. The stillsuit bulged in parts, deflated in others. Seals popped. Tubes ruptured precious water. The ragged armor fell away in pieces, exposing feminine thighs coated in desert-colored fuzz.

"What's happening?" Paul gasped. For the first time since drinking the Water of Life, he was surprised.

Lady Jessica did not blink. "There are two reservoirs the Sisterhood fears to draw from. The first, of course, is male Other Memory. The second is everything else. Non-human Memory. An abyss that surrounds our little islands of human recall. Less a reservoir, more an endless ocean in which many have drowned."

"But I know what you know. I should have seen this!"

"It doesn't occur in the Bene Gesserit genetic memory for a reason. Those who try it never go on to reproduce," she explained. "Not with humans anyway."

Now that he scoured his Other Memory more fully, there were shadows of it. Those who encountered the technique usually did so in the same way that a sentence encounters a full stop. Though there had been times when one Sister had stood in attendance of another Sister attempting it... and then had done everything to repress that memory.

The Animal Memory was stronger than he'd expected. The uncountable human lifespans that existed in his awareness were long and ponderous, each with their own unique essence, that he could sift through at leisure, like filtering a single voice in a crowd. The genetic memory of the desert mouse opening before him was less and so much more. A trillion tiny lives or the same life repeated a trillion times. A single voice drowning out the crowd. Birth, feed, breed, birth, feed, breed. Endless eons scurrying beneath sand.

His prana-bindu reflexes - those programmed instincts of biochemical control - responded automatically, his own perfect mastery turning against him, as muscle, bone and the chemical composition of his blood was bent to fit the new pattern.

His mother's face was a mixture of amusement and mild (though rising) concern. "Well? You are the Kwisatz Haderach, are you not? This should be trivial."