Video footage from a recent KSI gig shows the rapper stopping his performance to help a fan who had passed out, coming down from the stage to check out what had happened.
KSI - whose real name is Olajide Olayinka Williams Olatunji, or 'JJ' - was in Manchester on Tuesday 12 October, performing to a packed-out crowd at Manchester Academy on Oxford Road.
A 15-year-old called James had been near the front of the stage when he ended up passing out.
He later took to Twitter to ask if anyone had any footage of the incident so he could work out what happened.
James wrote: "If anyone who went to the @KSI show yesterday at manchester and filmed when he had to stop madness could you send it me please. i was the kid who passed out and would love to know what actually happened."
To his luck, it turned out another Twitter user called Arthur (@ATHRRRRR) had been filming, and sent him the clip.
In the video, KSI suddenly stops the concert and tells crew to pause the track.
"Pause it, pause it, pause it," he says, looking down at the crowd.
Addressing James, he asks: "Hey, yo, is my man over here good? Hey bossman, are you alright?
"Can we get someone to check him out?"
When another concertgoer starts chanting KSI's name, he shouts out: "Hey, how you doing bro? I just have to look after this kid real quick, man."
He then comes down off the stage and asks if the teenager should be pulled out of the crowd, watching on with concern as security staff come to assist.
Speaking to LADbible, James' mum said her son got too hot and hadn't drunk enough water.
Sharing the footage on his own timeline, James praised KSI's compassion, calling him a 'goat'.
He wrote: "It's so crazy to think how long I've waited to see @KSI live and I miss some of the show.
"However all props go to you @KSI for stopping the show and making sure I was all good and now I know I am your bossman [crying with laughter emoji].
"But in all seriousness you are a true goat."
His mum also tweeted the star to say thank you, writing: "Can I just thank @KSI, my son was at he's show tonight and @KSI stopped the show and jumped off stage to help him as he passed out!! Think it was being too excited and emotional after he met him, now that is a top bloke."