Elon Musk's biographer saw him fly into 'demon mode' where he suddenly becomes very 'dark'

A biographer for Elon Musk has revealed that the billionaire has a ‘dark’ side.

In fact, Walter Isaacson revealed that the SpaceX founder would often become ‘unpleasant' and go into ‘demon mode’ while focusing on a task.

If that weren’t bad enough the Twitter owner would even have ‘real lack of empathy’ for those who didn’t share his drive.

Ironically, Isaacson made the admission on the social media site during a Twitter Spaces interview on June 22.

The writer has been compiling a book on the Tesla founder, speaking with those closest to Musk – including his ex-partner Grimes.

Allegedly, it was the musician who made up the term ‘demon mode’ to describe Musk's states of hyperfocus – saying ‘it ‘gets s**t done’.

This state is reportedly ‘unpleasant’, with the billionaire having little empathy for those that don't have the same ‘maniacal sense of urgency’.

Due for release in September, Isaacson’s book also has another example of the bizarre behaviour by the multi-billionaire, who regularly goes ‘dark’ as he rips into colleagues.

Musk reportedly sacked roughly half of those employed at Twitter when he acquired the site late last year, so it seems he takes no prisoners.

"He'd go dark and I'd know that he was just going to rip that person apart," explained Isaacson in the interview – saying Musk was ‘just brutal’.

"The thing that I noticed is that once he finishes doing it — and it was never physical and it was almost done in a flat monotone — but he would just really attack people and then a few days later, if they absorbed the lesson, he'd forget about it,” revealed the biographer.

“It would be as if he went from becoming Dr. Jekyll to Mr. Hyde and then didn't even think that much or remember that much of how tough he had been on people."

Thankfully, the billionaire doesn’t behave like this constantly, with Isaacson stating that his criticism was only problematic ’20 percent of the time’.

Though this is unconfirmed, Isaacson states this ‘dark streak’ comes the bullying Musk endured as a child and intense home life.

"Elon Musk also has a desire for drama, both in his personal and in his professional life," added Isaacson: "He is somebody who feels most comfortable when he's ordered up a hurricane or surge."

UNILAD has reached out to Musk for comment.