SEE IT: Trump meets young supporter with rare brain disease backstage at rally

An 8-year-old boy received the surprise of his young life, after former President Trump greeted him in person during his rally Wednesday in New York.

Liam, who has a rare brain disorder, was recently given a letter from Trump just before his eighth birthday and his heartfelt reaction to the surprise went viral.

Doctors warned the family Liam might never walk, talk or eat on his own, according to his mother, Siobhan. 

"My buddy here plays ice hockey, he does roller hockey, he does very good in school, plays sports…we’re so proud of him," she told Fox News Digital in an interview moments before Trump’s rally at Nassau Veterans Memorial Coliseum in Uniondale near the family’s Long Island home.

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Former President Trump surprises 8-year-old Liam prior to taking the stage during his New York rally on Wednesday night. (X / @kevin_smith45)

Liam's mom said he has been a Trump supporter since he was 18 months old. 

Less than a week after receiving the letter, Liam's family was invited to Trump's Unidondale rally as VIP guests, where Liam received an even bigger birthday gift by meeting the Republican presidential nominee. 

"I'm supposed to be on that stage, but that doesn't matter because I got you the best present. This is the best present you'll ever have," Trump said while greeting Liam backstage.

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Liam and his family were special guests for former president Trump at his New York rally on Wednesday evening.  (Julia Bonavita)

Trump handed Liam a box and said "in there is real good stuff." 

"We're gonna have that picture for life, you and I," Trump told Liam after taking a photo.

Trump thanked Liam and his family for joining him.

"Take care of yourself, okay? I wish I looked like that or if I looked like that, I'd be president," Trump told Liam. 

Trump also gave Liam and his family a shout-out during the rally, telling the crowd about Liam's bravery and their visit while pointing him out from stage while the crowd erupted in applause.

"I'm in tears," Liam's mom told Fox News Digital. 

The original viral video, which caught national attention, showed Liam eagerly opening an envelope with a letter addressed to him from the former president. 

"This is a side of Donald Trump that nobody gets to see," said Kevin Smith, who shared the original video before it blew up online. "Most Americans, he said, only see Trump’s public persona and widespread media coverage."

Donald Trump took time to surprise Liam, an 8-year-old fan, prior to going on stage at a rally Wednesday in New York. (X/@kevin_smith45)

The video opens with Liam sitting on a couch as his mom hands over the envelope. She asks if he wants to read the letter or have her read it, as he fights back tears realizing what is happening. 

"Dear Liam, Happy birthday, Mrs. Trump, and I hope you enjoy this special occasion surrounded by the love of your family and friends," Liam's mom, Siobhan reads.

"We are so encouraged by the strength and determination you have shown throughout your life and send our love and best wishes to you as you continue to fight," the letter continued. "Remember you are never alone, and we are keeping you in our thoughts and prayers for continued care and good health. May God bless you and your family, stay strong."

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Charlie Kirk, founder of Turning Point USA, shared the video and praised the former president for his thoughtful actions.

"Wow. This is one of the most incredible videos you'll see. This little eight-year-old boy with a rare brain disorder breaks down in tears when he opens a letter from President Trump wishing him a happy birthday," Kirk wrote in a post on X. 

Siobhan then mentions that Trump knew Liam's birthday was coming up and asked him how he felt about him wishing him a happy birthday.

"Sincerely, can you tell me who signed that?" Siobhan asks.

"Donald Trump," Liam responds shakily, holding back tears. 

"He knew it was your birthday coming up? What do you say to him," Siobhan asks.

"Thank you, I love you," Liam says while also signing "I love you."  

Fox News Digital's Julia Bonavita and Sophia Compton contributed to this report.