The family of a terminally ill boy who charmed a Hollywood superstar says their boy is the real superhero.
Aaron Hunter suffers from a rare condition that will see his health continue to deteriorate.
He started a campaign to raise awareness and appealed to his hero Iron Man to help him stop his friends from dying.
His mum and sister have spoken for the first time about what the involvement of actor Robert Downey Jr has meant to them, to Aaron and to the help group they set up to create awareness.
Aaron suffers from ROHHAD (Rapid-Onset Obesity with Hypothalamic Dysfunction, Hypoventilation and Autonomic Dysregulation), a rare condition which causes children to gain weight and develop breathing difficulties.
It is so rare it affects only one in 73 million people and there are only about 100 confirmed cases worldwide. There is currently no cure.
Robert Downey Jr, who stars as Iron Man in the Holywood movies, became a fan of Aaron Hunter after the eight-year-old asked him to support a charity pressing for more research into his condition in a video.
He got in touch with the family and became firm friends with Aaron before meeting them in person and making a film where he jumped in muddy puddles as part of Aaron's muddy puddle challenge.
Aaron's 13-year-old sister Lauren told the BBC: "Aaron adores him - it's like they have a special connection. They've been facetiming for ages now so they've gotten to know each other.
"But when they met it's like they had a physical connection to each other - he is a great man and we are so grateful."
Mum Elisabeth said Aaron even asked the actor if he would adopt him. Elisabeth said: "Aaron believed from the very beginning if he could speak to Iron Man or Iron Man read his letter or saw his video then he would help him because that's what the good guys and the heroes do.
"He said we need to do a challenge and get Iron Man and the Avengers to do it."
The youngster came up with the muddy puddle challenge and decided to challenge Iron Man and the Avengers.
Elisabeth hoped for the best and for a while thought they wouldn't reach the actor, but Aaron always believed and knew it would happen.
I may play Iron Man, but Aaron is the true hero. Go to https://t.co/ywpvrsejuv to see the full story. Donate to @ROHHAD_Global and help Aaron and his friends fight on. Every $10 is a chance to join me at #AvengersInfinityWar premiere.#randomactfunding #findacure 🎥@kevinfordmedia pic.twitter.com/H7rqVIRX72— Robert Downey Jr (@RobertDowneyJr) March 30, 2018
She says the moment they met will always be a special memory for her.
"Robert told us he watched the video and asked: 'Who is this kid asking for help for others?'
"He was touched by how determined he was to help other people.
"I'll never forget the day they actually met and how sparkly Aaron's eyes were.
"We will always have that memory - no matter what.
"Now, even if Aaron loses his life to ROHHAD he will always have that time with Robert...with Iron Man."
Aaron, from Alexandria in West Dunbartonshire, was diagnosed with the condition at the age of five after three years of symptoms developing and a lot of hospital stays.
It took so long to pinpoint because there is so little research on the illness and no test for it.
ROHHAD is progressive, so Aaron's health will deteriorate.
'A beautiful place'
But Elisabeth and Lauren say he never complains and won't let his illness hold him back.
Elisabeth said: "We never get through a day without a smile from him."
She also knows that, without further research and understanding of the condition, he will continue to decline.
"I don't allow myself to think too much about losing Aaron.
"We founded the ROHHAD Association for a good reason and that reason was to help the children affected round the world.
"He's not worried. He has told us a few times that heaven's a beautiful place so don't worry when the time comes.
"For us, Aaron was our driving force to help families around the world. He keeps us going.
"Thankfully because of Robert, and him helping us raise awareness, we are now full of hope that we might not lose him and that we will be able to help the other children as well."