[2][3] He is a random element not foreseen by psychohistory, a science developed by Hari Seldon which uses sophisticated mathematics and statistical analysis to predict future trends on a galactic scale.

[3] Posing as a clown named Magnifico Giganticus who is escaping the Mule, he is described by Asimov as "spindly", with "long, lean limbs and spidery body" that seemed "thrown together at random.

"[5] Josh Wimmer and Alasdair Wilkins of Gizmodo wrote that the Mule's mutant ability to control the emotions of others and convert his enemies to loyal followers makes him basically invincible to all opponents and unpredictable to the Hari Seldon's plans.

[5][6] He employs this method to sow despair throughout the Foundation homeworld Terminus and the Trader planet Haven, and to kill the nobles in Neotrantor, the last bastion of Imperial rule.

"[6] Folk-Williams wrote, "The Mule, at least early on, comes across as a figure of some complexity, burdened by loneliness and self-doubt, as well as possessing deep insight into the people around him.

"[5] Don Kaye of Den of Geek described the Mule as enigmatic, elusive and "obsessed with finding the Second Foundation, which he fears could defeat him.

Foundation-aligned newlyweds Bayta and Toran Darell investigate, soon leaving Kalgan with the Mule's fugitive court jester, Magnifico Giganticus, a "strange, gangly creature" who speaks "in rather contorted, vaguely literary language."

At what remains of the Great Library of Trantor, Mis works tirelessly to discover clues to the secret location of the Second Foundation.

He is a mutant who can sense and manipulate the emotions of others, an ability he has employed to conquer planets bloodlessly, to "convert" Foundation intelligence officer Han Pritcher into a loyal agent, and to compel Mis to work himself to death.

The Mule promises to find and destroy the Second Foundation, the only threat to his eventual reign over the entire galaxy, but Bayta asserts that it has already prepared for him, and will react before he has time to stop it.

Secretly followed by the Mule and his fleet, Channis leads the search to the desolate planet Tazenda, a plausible location for the Second Foundation.

When the Mule experiences a moment of despair, the First Speaker is able to seize control of and alter his mind: he will return to Kalgan and live out the rest of his life as a peaceful despot.

[10][11] Determined to destroy the Foundation and kill Salvor Hardin,[11] he is described as "a monster of a man, coiled with muscle and possessing powerful psychic abilities, and fueled by hate in his quest to take over the galaxy.