Some surprises are just too stunning to take in all at once. That was the case Thursday for Leo Medina, 5, of Nesconset, one of the kindergartners waiting for the ice cream to be served at Tackan Elementary School’s winter festival in Smithtown.

Had he been older — the photographers focused on him, prompting Leo to briefly cover his face with his red bowl — he might have figured out the promised surprise was not a visit from Santa, as was rumored.

Rather, it was his big brother, U.S. Army Pvt. Justin Purnell, 18, home on a two-week leave after his first stint at boot camp at Fort Benning, Georgia, who came strolling down the hall and into the cafeteria.

“It took Leo like a second to realize who it was,” said the boys’ mother, Nicole Medina, 42, of Nesconset.

Leo stayed in his seat until a teacher asked if anyone recognized the visitor. “Oh, I do,” he answered, and then jumped up and marched to his brother, who swept him off his feet in a bear hug.

“To see his jaw drop and see him run — it just lights you all up inside,” his mother said.

Her two boys might be 13 years apart, but they are unusually close: their mother, a single parent with a demanding career as a phlebotomist, calls Justin her “co-parent.”

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When she was at work, Justin escorted Leo to and from the school bus, gave him meals, helped him with homework and even went with his younger brother to the doctor on occasion.

“Can I go now? Can Justin have ice cream?” were Leo’s first audible questions after he was back on his feet.

The answers were yes, but only Leo got to finish his ice cream.

The public relations duties of camouflage-clad soldiers out among civilians include patiently answering repetitive questions from reporters — and getting lots of enthusiastic high-fives from excited kindergartners.

“It hit him hard,” Justin said, describing Leo’s reaction to his absence. Their mother said her kindergartner has struggled to accept that he can neither call nor visit Justin.

And Leo, it seems, by nature is a little reserved.

“I know when he goes home he’s going to be all excited, like, ‘Do you want to do this, do you want to do that?’ ” Justin said.

When it comes to surprises, this soldier, a 2016 graduate of Smithtown East High School, is on a roll.

His girlfriend, Kim Lawless, 18, of Smithtown, thought she and Justin’s mother would be going out to lunch when her mother asked her to “Come downstairs.”

“He surprised me, too,” Lawless said.

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Though Justin’s mother said her family hates surprises, they hoped to pull off two more: grandmothers Roberta Kosiorowski of Smithtown and then next week Norma Pendleton of West Orange, New Jersey.

They hoped to catch Kosiorowski off-guard at the afternoon basketball game at Smithtown East, where her niece will perform in a kick line.

“I think he’s just going to walk in and kind of like look for her,” Medina said, stressing her gratitude to the Tackan staff for going way beyond her initial request that Justin just be allowed to be a “surprise reader” for Leo’s class.

If the family’s luck holds, Justin next week will surprise Pendleton.

Justin, whose mother said he always wanted an Army career, was taking the rigors of boot camp in stride, pleased with his improved fitness and accepting of the discipline.

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“I don’t say ‘Yeah,’ anymore, I call everyone Sir and Ma’am, and I speak properly. I really lost a lot of weight; they mess you up but it’s to build you up.”

His immediate future could include some horseplay. Leo said he is looking forward to wrestling with his big brother.

Asked who might win, he replied: “It’s a tie; can I go now?”

Justin’s leave was perfectly timed for his mother.

“To have him home for Christmas is the only thing I wanted — and I got it.”