Ari has been battling cancer for eight years after being diagnosed with neuroblastoma - a childhood cancer that affects nerve cells but can travel all over the body - when she was just three years old. She has relapsed four times and is currently doing well.
For more details on her memorable story and to see the emotional video when she learned about her trip, check out our earlier story about Ari.
1:30 p.m. CT
Ari arrives at the airport with everything she needs for a Blues' road trip: a suitcase, blue nail polish (for her Blues!), a No. 91 jersey, her doll (whose name is Chelsea) and her mom, Lori.
As she sits in the lobby waiting to board, she's greeted by just about everyone on the team, from Ryan Reaves and Carter Hutton to John Kelly and Darren Pang to GM Doug Armstrong and Hall-of-Famer Al MacInnis.
But it's Vladimir Tarasenko she's most excited to see.
Tarasenko walks into the lobby around 1:40 p.m., gives Ari a big hug and helps her carry her belongings onto the plane.
Once aboard, Ari helps the flight attendants demonstrate safety instructions, showing the players how to properly latch their seat belts, how to use their oxygen masks if needed and pointing out all of the emergency exits.
After that, she's off to Arizona!
2:15 p.m. CT
30,000 feet above mid-Missouri
Ari gets situated on the plane and has a comfy Vladimir Tarasenko blanket just in case she gets cold. She won't need it when the plane lands because it's 80 degrees where she's headed.
Around 2:30 p.m., she goes to the back of the plane to play card games with Tarasenko. She brought the game "Rat-a-Tat Cat" with her and has to teach him how to play. Luckily, she brought the Russian language version of the instructions to make it easy for him.
They play two games. The first one ends in a tie, probably because Ari is saving all of her tricks.
But the second game? Ari wins!
5:05 p.m. CT
Somewhere over Arizona
Ari baked some chocolate chip cookies for everyone on the plane!
3:20 p.m. PT
Phoenix Sky Harbor Airport
Ari and the Blues land in Phoenix and board a bus to the team hotel, where they can relax for the evening before a big game tomorrow against the Coyotes.
10:20 a.m. PT
Gila River Arena
It's gameday and Ari is ready to go!
She has breakfast in the morning, then gathers her belongings for the short walk to Gila River Arena, where she'll watch the morning skate.
While she's on her way, a Blues fan asks to take a picture with her. Who knew that traveling with the team would also make her a big celebrity?!
Ari is equipped with a Blues stocking hat and a pink Blues jersey, which she plans to wear to the game. Her doll - Chelsea - is also coming to the morning skate, and she's wearing a Blues jersey and a goalie helmet just in case any pucks come flying in her direction.
Ari says hi to the players from the stands as they step onto the ice for practice. Vladimir Tarasenko stops to give her a high-five and asks what her plans are for the afternoon.
"We're going to the botanical gardens," she says.
"Have fun," he says. "Hopefully we're gonna win."
Tarasenko goes to the locker room to shower, then comes back to say bye. But Ari has a surprise for him - she's convinced the FOX Sports Midwest camera man into giving her a microphone so she can do an interview for the pregame show!
Video: Ari interviews Tarasenko on FOX Sports Midwest
12:30 p.m. PT
Outside the Blues locker room
Video: Mike Yeo is excited to have Ari on the road trip
Blues Head Coach Mike Yeo conducts his routine game day interview with the media and mentions he's happy to have Ari around for the game.
"She's a sweetheart. She's a great kid and it's fun to be around her," Yeo says. "We know what she's gone though, but her attitude and her personality, she's one of the happiest people you could meet… It's great for our team to be doing this type of thing for a person like Ari… (I hope) that we play a real good game for her and make this experience as great as we can."
5 p.m. PT
Dinner with an old friend
After some fun in the sun, Ari and her mom, Lori, have dinner at a Mexican restaurant near the arena, where the Blues are warming up to play the Coyotes. Ari knows its a big game for her team, who could clinch a playoff spot with a victory and a little assistance from the Calgary Flames.
At dinner, Ari is joined by another one of her friends - former St. Louis Cardinals pitcher Jason Motte. The two became friends about five years ago when they met at a charity wiffle ball tournament in St. Louis.
"Ari was always smiling, always happy, just the way she is now," Motte said. "I went over and said hi and we got to talkin'. She actually brought me a tiara the next time, so I walked around with my beard and my tiara on. But today, I have a bedazzled Blues scarf!"
Motte is able to join Ari because he's been in Phoenix for spring training. In fact, he was packing up earlier Wednesday to get ready to return to Colorado, so the timing couldn't have been better.
"Anytime I get to hang out with Ari, it's awesome," he said.
After dinner, they're headed to Gila River Arena to cheer on the Blues.
7 p.m. PT
Warm-ups and game time
Ari and Jason Motte have the best seats in the house for warm-ups, as the Arizona Coyotes generously allow them to watch from the penalty box.
After that, it's up to a suite at center ice, where they'll watch the game.
Patrik Berglund scores in the first period to give the Blues a 1-0 lead. At intermission, the Coyotes in-game host and Howler the Coyote come to visit in the suite and even bring a few gifts. And even better, Ari gets to do an intermission interview on the Jumbotron!
Video: STL@ARI: Tarasenko scores goal for special guest Ari
In the second period, Vladimir Tarasenko scores for her. Ari cheers and waves her towel. Playoffs are just around the corner, so she'd better practice her rally-towel waving.
The Blues give Ari a 3-1 win - their 11th straight against the Coyotes - but are unable to clinch a playoff spot due to the Los Angeles Kings winning against the Flames.
But for Ari, that's OK. Her Blues can still clinch on Friday.
10:30 a.m. PT
Phoenix to Denver
It's time to leave Arizona, and Ari has some additional carry-on luggage: two giant emoji pillows that she won after a night of arcade games at Dave & Busters on her first night in Phoenix.
As the plane takes off for Denver, GM Doug Armstrong's water bottle falls off his tray table and rolls down the center aisle.
This gives Ari an idea!
She asks for a pen and writes "Hi from Ari" on her own water bottle, then attempts to roll it down the aisle to the back of the plane where Vladi sits.
Blues captain Alex Pietrangelo notices and stands up to help. As Ari rolls the bottle, Pietrangelo plays the relay man who tries to steer it back to Vladi's seat.
Their attempts are not successful, but it doesn't matter. A few minutes later, Vladi is coming to hang out.
Before the plane lands, Ari makes a tray of what she calls "Ari Bars" and offers them to everyone. "Ari Bars" consist of graham cracker crust, white chocolate, dried cranberries, coconuts, chopped pecans and sweetened milk.
1:10 p.m. MT
Denver International Airport
Ari and the Blues land in Denver and board a bus bound for the team hotel.
2 p.m. MT
Team hotel in Denver
After carrying in her luggage (and one of her giant emoji pillows), Ari walks into the team's hotel in Denver and takes the elevator to her room.
When she opens the door, she's amazed at what she sees!
The hotel staff in Denver had seen her story online and decorated her room with a giant banner that says "WELCOME ARI." The banner is signed by the entire hotel staff.
10 a.m. MT
Bus to the morning skate
After a good night's sleep, Ari is up and excited for the final day of her road trip. She high-fives each of the players as they get on the bus for practice, and during the ride, she sits with Jordan Schmaltz and Ivan Barbashev to test them with some riddles.
Here's the first one:
"There's a one-story pink house. Everything in it is pink. The house is pink, the table is pink, the faucet is pink, the sink is pink, the toilet is pink. Everything's pink. So what color are the stairs?"
"Pink?" Schmaltz asks.
"No!" Ari says. "It's a one-story house. There are no stairs!"
The jokes and riddles continue, but Schmaltz and Barbashev don't have much luck with any of them.
In 10 minutes, the bus has arrived at Pepsi Center. Ari walks in to find the Blues' video crew waiting for her to tape a new episode of Bommarito Zero to Sixty, and she's the special guest!
Video: Ari is the guest of Hutton and Reaves
7 p.m. MT
It's game time! Ari jumps up and cheers when Ryan Reaves scores first - which is especially cool since Reaves predicted he'd score for her in their Zero to Sixty episode.
At the beginning of the second period, she's on FOX Sports Midwest with John Kelly and Darren Pang, saying hi to all of her friends and nurses watching at home.
Video: STL@COL: Ari Dougan on the road trip with Blues
Soon after that, she's on KMOX radio calling the game for Chris Kerber and Kelly Chase.
LISTEN: Ari does play-by-play on KMOX radio
The Blues don't win the game, but they do get to overtime to secure a point. For Ari, that's good enough.
"Holy jumpin! We're in the playoffs!" she says.
11:11 p.m. MT
Waiting for take-off
Tarasenko has another surprise for Ari. He gives her two of his Russian hockey cards to keep and asks her if she wants to play cards or rest on the late flight home.
She's a gamer. She picks cards.
GM Doug Armstrong comes to thank her for coming on the trip and bringing the team some luck. Ari gives him a wristband that says "Fight like Arianna. Always with a smile!"
11:30 p.m. MT
The flight home
While words could never completely convey just how much joy Ari has brought to our team over the past few days, perhaps this final blog entry will help provide some insight into just how special this little girl is.
On the first night of the road trip, a group of Blues staff members took Ari and her mom to dinner at Dave & Buster's in Glendale. Afterwards, everyone spent an hour or two playing games in the arcade to try and earn enough tickets to help Ari win two giant emoji pillows she wanted from the gift shop: one with sunglasses and one with heart-shaped eyes.
We left Dave & Buster's with both emojis in hand. Since then, Ari has carried the emoji with sunglasses everywhere she goes, but she's been hiding the other one.
We asked her why, and her answer nearly brought us to tears.
Ari said she didn't want Vladi to see it because it was a gift for him - her way of saying thank you for bringing her along for the trip.
On the back, she wrote the following message: "To Vladi: Thank you for an awesome trip! Love, Ari"
"After I got this trip as a present (from Vladi in February), I went into the hospital for a week," Ari said during an interview with our camera crew. "(Vladi) got me looking forward to the trip and got me through some of the harder times that I had."
"Just knowing Ari is here is that much more incredible, because she's not really supposed to be here," said her mom, Lori. "Based on her diagnosis and what she's been through, most kids that have neuroblastoma don't make it five years once they've relapsed. So the fact that eight years later she's still here and getting to smile and getting to feel good enough to do something like this, it's just more than I can handle sometimes. It's amazing."
Tarasenko left the airport on Saturday morning around 2:30 a.m. CT carrying his luggage and his giant emoji home.
Those big heart-shaped eyes are no match for how big his heart is.
"'Thank you' doesn't seem like it's enough," Lori said. "I want (Vladi and the Blues) to know how special this was and how much this meant to her. She'll be able to talk about it and look at the pictures and share everything, and people will recognize her. All of those things add to her feeling better. I truly believe these kinds of things make her healthier and make her more successful in beating this cancer."
Good luck in your battle, Ari. And thanks for spending the past four days with us.
We might have enjoyed this trip even more than you did.