TEMPE, Ariz. -- Delilah Cassidy's tweet thread was building to a climactic ending.

At 1:37 p.m. on May 30, Cassidy, a law student at Arizona State University, began tweeting about her experience at an airport gate en route to Phoenix from a European trip. By now, the story is internet lore.

But that afternoon, she was unveiling it to the digital world tweet by tweet. She was about to board an American Airlines flight when the gate agent told her she needed to pay $50 to bring her carry-on with her. If she didn't want to pay, the agent said, she needed to check it at the counter -- which would've caused her to miss her flight. A stranger standing behind her offered to pay the fee, allowing Cassidy to get on the flight and return home.

In the seventh and final tweet of the thread, Cassidy revealed the mystery donor was Arizona Cardinals tight end Jermaine Gresham.

Update: It was Jermaine Gresham. pic.twitter.com/aJ0bXoNm8Q — Delilah Cassidy (@Delilah_Cassidy) May 30, 2018

Then the internet exploded.

The tweet with a selfie of her and Gresham has more than 5,700 retweets and almost 42,000 likes. Cassidy's story went viral, and Gresham was hailed as a kindness hero.

"I just feel like it's just how I was raised," Gresham said in his first public comments since the gesture. "Core values. You see somebody in distress, just help them out. Nothing more, nothing less."

But his random act of kindness in the airport wasn't the first time Gresham had done something nice for somebody else. Sitting among the 463 comments were others.

He walked into my nail salon in Scottsdale one time and paid for random people's nails 😭😭 seems like a great guy — peyton d (@peeeyyy) May 31, 2018

Class act. True story: At a supermarket in Tempe a woman who looked down on her luck was buying milk, bread and some diapers. She was fumbling through her purse searching for change to have enough to pay. Jermaine Gresham (who was behind me) pushed through and paid for everything — IfURnotwastdthedayis (@FellNcantgetup) May 31, 2018

The tweets of his kindness kept coming. Most people were just learning about this side of Gresham, but that's always who he has been, said his mother, Walletta Gresham.

He gets it from her mother -- his grandmother -- who got it from her mother. Jermaine's great-grandmother ran a nursing home in Ardmore, Oklahoma -- Jermaine's hometown -- Walletta said. Walletta watched her mother let people who needed a bed stay with her and make sure they were fed.

Kindness was passed down through the Greshams.

"It's just something that's embedded in us," Walletta said.

He always has been like that, she said. She tried to think back to the first time she saw Jermaine's kind side. Too many instances ran together.

"I'm his mother," she said. "I've been knowing that all my life."

When Gresham was in Cincinnati I saw him take three homeless people out to eat and he took them to buy new clothes — Derick Smith (@DerickSmith91) May 31, 2018

When the Range Rover pulled into the driveway at the Millennium Hotel in downtown Cincinnati, Derick Smith, who worked as a valet, didn't know who would open the driver's door.

For years, the Millenium had become a go-to destination for professional athletes in Cincinnati to park their cars when they visited downtown. They knew if they tossed the valet $10, $15 or $20, they could park their cars in the driveway for about two hours while they rendezvoused around the city. That day during the 2015 offseason was no different.

Out from the SUV stepped Gresham. He asked if it was all right if he parked there. Smith was quick to say it was. But that's not what surprised Smith -- it was who else got out of the car.

Two men and one woman also got out. All of them, Smith described as white and middle-aged. "They had a very dirty smell," Smith said. "They looked like they hadn't bathed for a couple of weeks, kind of had some old, ratty clothes on -- they weren't necessarily tattered, but they had holes in them. But you could tell they were dirty and old."

Smith said he wasn't sure if the passengers were homeless, but when Gresham asked if he could park at the hotel, he followed that by saying he was going to take the three people to eat and to get some clothes. And down the street they walked, Smith remembered.

"He acted like it was normal," Smith said. "He acted like it was just plain as day. It was just odd because you didn't expect to have these three homeless people walk out of a brand-new Range Rover."

I met him a few years ago at my friend's party in Ardmore, OK. Couldn't have been a nicer guy. He bought pizza for the people who were too drunk at the party...even though he didn't drink a sip of alcohol. Great sooner! — Matthew Wideman (@MattWidemanAtty) May 31, 2018

One of Matt Wideman's best friends from his undergraduate days at Westminster College in Missouri just happened to grow up in Ardmore, Oklahoma, the same hometown as Gresham.

Although he is several years older than Gresham, their circle of friends overlapped. So, when Wideman's friend hosted a housewarming party in March 2011 in Ardmore, the invite list, which was about 30 people long, included some people who knew Gresham. At one point during the party, they asked if Gresham could swing by. A die-hard Oklahoma Sooners fan, Wideman's friend enthusiastically welcomed the tight end.

Wideman remembers Gresham showing up around midnight -- about four hours after the party began. He declined all the drinks offered his way, though, telling guests he doesn't drink, Wideman said.

"He was probably the nicest, warmest, very friendly guy," Wideman said. "He was super cool."

In the early-morning hours, Gresham -- unprompted -- offered to buy the partygoers pizza, Wideman said. A little while later, about $100 of food was delivered to the house.

"Nobody asked him to," Wideman said. "Nobody said, 'Hey man, we're broke.' He just did it. He was like, 'Hey, it looks like everybody had too much to drink, I'll just make sure everybody gets home safely.'"

But one memory from that night that still sticks out to Wideman is that Gresham, who stayed about two hours, wouldn't eat any of the pizza. He wanted everyone who was drinking to eat it, saying he was in training, so he was staying away from pizza.

Watching Gresham that night, in the middle of the offseason, in the middle of Oklahoma, in the middle of a stranger's house, showed Wideman who Gresham was as a person.

"You can pretend in the news, you can pretend in an article talking to you, but it's hard to pretend on a Tuesday night, it's hard to pretend on a Thursday night."

Such a great guy! Gresham came up to me in LA a couple years back and spent some time talking to be before the game. He's got such a big heart I'm glad he's a Cardinals — Claudia Schwartz (@SchwartClaudia) May 31, 2018

Claudia Schwartz and her father made sure to get to the Los Angeles Coliseum "pretty early" before the Cardinals' Week 17 game against the Rams to close out the 2016 season so they could secure a spot on the railing during pregame warm-ups.

Her mission that day was to get autographs.

What she got, however, far exceeded her goal.

When Schwartz saw Gresham run onto the field for warm-ups, she screamed his name while holding a Cardinals flag. Gresham turned and waved at her. About 30 minutes later, Gresham went to Schwartz and her dad en route to the locker room. She asked him to sign her flag, which she said he graciously did, and then, much to her surprise, he struck up a conversation.

"He was like, 'Where are you from?' and he was asking me all of these questions," she said. "I want to say we ended up talking for like 15 minutes before the game, and it was just, like, random questions about my trip down to L.A. and how I was. I was like, 'I'm so excited to watch you guys next season,' and, 'This was my first time in L.A.'

"Just random conversation, but it was so nice of him."

Schwartz and her father, who have lived in Colorado for seven years after she grew up in Arizona, try to go to two Cardinals games a season. When players signed autographs for her during pregame warm-ups in the past, they usually didn't take off their headphones, she said. Gresham took the time to chat.

"He was just like, 'Oh, are you from down here? Where are you from?'" she said. "I was just like, 'Whoa, wait. Did he just ask me that? I was so surprised."

She wasn't the only one surprised by Gresham.

Cardinals tight end Jermaine Gresham hands a football to a young Falcons fan after Gresham had scored a touchdown during a game in Atlanta in November 2016. Frank Mattia/Icon Sportswire

Take a spin around the internet and there's more. Gresham once gave a homeless man $100 after the man put 50 cents into his parking meter so that Gresham wouldn't get a $55 ticket. He replaced a football that a Saints fan stole from two Bengals fans in New Orleans in 2014. He sent autographed jerseys to winners of a youth football league. And Gresham has donated at least $60,000 to his alma mater, Ardmore High School, for uniforms, gear, apparel and equipment for the football, boys' basketball and girls' basketball teams.

Gresham has made an impression wherever he has been. A.J. Moreno, a volunteer with the Sooners football program while Gresham was at Oklahoma, remembers how Gresham acted toward the fans, people in the football offices and, especially, coaches' kids.

"The big word I can think of is humble ... and down to earth," Moreno said.

Now that Wideman is about seven years past meeting Gresham at that house party, he appreciates what Gresham did even more.

"As I'm older and I see how people truly are, it's really kind of mind-blowing in some ways," Wideman said, "because here's a guy, a multimillionaire, coming to a party for two hours, buying a bunch of kids pizza, and for really no reason other than making sure they get home safe.

"It's almost like an astronaut coming to your high school."

And their interactions with Gresham left those people lifelong fans of his -- both on and off the field.

Wideman said he'll always draft Gresham in fantasy football now, regardless of how well he has been playing. Asked if he's more of a fan of Gresham now, Smith said, "Yeah, big time."

"It's nice to root for someone who you know is going to come into the community and do his best to give back."