Season finale at Sonoma, Calif., 6:30 p.m. Sunday, NBCSN

INDIANAPOLIS – The line of well-wishers waiting for autographs outside his transporter are getting longer each week. The number of fans wearing his gear seems to grow every race.

In just a few short years, Alexander Rossi has transformed himself from IndyCar’s great unknown to a building block for the future and one of its most marketable stars.

“It’s been very cool for me to see from Year 1 until now — almost the end of Year 3 — the amount of people wearing my shirts and hats and wanting to talk to me at autograph sessions,” Rossi recently said in Portland. “That’s really increased.”

The road here hasn’t been easy. There was a time when Rossi seemed to be almost universally disliked by the IndyCar world. But whether he meant to or not, over the past three years, he’s turned many of those doubters into believers.

***

One of IndyCar’s most beloved personalities could not stand Alexander Rossi. That might be underselling it, actually. Tony Kanaan hated him.

“In my defense,” Kanaan says with a chuckle, “I’m not the type of guy to hate people. But we really didn’t see eye to eye there in the beginning.”

Kanaan thought Rossi was a punk. A cocky kid who didn’t care about the sport or the drivers who had poured their blood, sweat and tears into it for decades.

Rossi’s rookie year, 2016, the two seemed to lock horns every Sunday, and rarely did the laid-back Californian show Kanaan the amount of respect – on track or off it – he felt he had earned.

“I remember going to talk to him once in that first season after something happened, and he was like, ‘Eh, I was racing.’ Kind of like, ‘What? It’s not a big deal,'” the 43-year-old Brazilian remembers. “And you’re like, ‘(Expletive) off man. It is a big deal.’ I was like, ‘Who the hell do you think you are?! I’ve been doing this for 19 (expletive) years. Give me a little more respect.’”

Sonoma storylines:Championship up for grabs as silly season chugs along

More:What you need to know about IndyCar title contenders Dixon and Rossi

Kanaan pauses here before he starts laughing.

“I’ll say this about him, he didn’t give a (expletive)," he said. "(Rossi) was like, ‘To be perfectly honest, man, you can be whoever you want, I’m going to race you as hard as I can.’ … That’s my assessment of Alex. He’s just a hard racer. … He’ll push the limit, and that did not sit well with me the first year he was in the series.”

James Hinchcliffe can relate. Before they became close friends who co-host a popular podcast together, Hinchcliffe, wasn’t exactly a fan of Rossi's.

He wouldn’t say he hated Alexander Rossi, but when they first met almost three years ago, Hinchcliffe probably wouldn’t have minded if the Manor Racing reserve driver had packed up his bags and went back to Europe. That’s where he wanted to be anyway. At least it seemed that way.

“When I first met Alex, he had just signed up for the first season in 2016. I think it was February or early March or something like that,” Hinchcliffe recalled. “He definitely had this aura around him. It was like this year was an inconvenience, just a stopgap until he could get another crack at Formula One.

“I didn’t love that. I don’t think anyone did because it was kind of belittling what we do. He wasn’t outwardly, verbally saying it, but you could see it in his body language. You know?”

IndyCar fans know. In fact, it was that same body language that irritated so many of them after Rossi won the 100th running of the Indianapolis 500 his rookie season. Not only did he fail to go berserk in celebration, a la Kanaan in 2013, but to many, he looked like he didn’t even care. Like the whole thing hardly registered. He didn’t know about the milk or the wreath or any of the other sacred rituals.

His naivety, combined with his often deadpan demeanor, was painted as indifference.

But that wasn’t fair, Rossi would later say. Not knowing isn’t the same as not caring. He had only just begun to understand the meaning of Memorial Day weekend in Indianapolis and just how challenging and how competitive the series, which was now his duty to promote, actually was.

“I don’t think people’s perception (of me) was very good,” Rossi said recently. "Or very fair."

***

One race, Hinchcliffe said. It took Rossi one race to understand that Indy car wasn’t just an easy steppingstone back to Formula One.

Their first encounter didn’t go so well but Hinchcliffe will never forget their second either.

“He said, ‘I’m never ever going back to Formula One,’” Hinchcliffe remembers Rossi saying following the 2016 season-opener on the streets of St. Petersburg, (Fla.). “For me, that was big.”

Rossi's eyes were opened that day, added then-Andretti Autosport teammate Townsend Bell. While Formula One boasts some of the most talented drivers in the world, Rossi learned that day that those on this side of the pond are pretty darn good, too.

It was a hard lesson learned, Bell said. It likely wasn’t easy for Rossi, at the end of the race, to allow leaders to lap him and fight for a victory he was nowhere close to attaining.

“I’ll never forget that moment in the race because it was kind of that sink-or-swim moment for any rookie coming into the top level of any sport,” said Bell, now a NBCSN IndyCar analyst. “It’s an eye-opener, when you realize how deep the pool is or how deep the competition is. Then it’s, what are you going to do about it? How are you going to go back with your team and analyze your performance and come back stronger?”

Answering that question became Rossi’s obsession. After that first race in St. Petersburg, he put Formula One in the rear-view mirror and worked tirelessly to ensure his days as an IndyCar backmarker were short-lived. And, of course, they were. His progression inside the cockpit has been nothing short of exceptional. In nearly three complete seasons, he’s taken five checkered flags and podiumed 12 times, each one more than Scott Dixon achieved in his first three Indy car seasons.

At just 26 years old, Rossi’s become the top dog at Andretti Autosport, which features another annual championship contender and fellow Indianapolis 500 winner in Ryan Hunter-Reay. And if Rossi were to overcome Dixon’s 29-point lead Sunday, he’d become the fastest to claim an Indy car series championship since Sebastien Bourdais dominated CART in his second year (2004).

“In three years, he’s now met and in some cases exceeded the measure of Scott Dixon, the established milestone, the established marker in the series,” Bell said. "It’s so cool that we’ve got a young American who has basically stopped pursuing a European F1 career to come be an IndyCar champion, and he’s on the verge of making it happen this weekend.”

What’s more, Rossi's progression outside of the cockpit mirrored his progress in it. To say he’s beloved by everyone in the paddock probably wouldn’t be accurate, but he’s no doubt changed the minds of anyone who questioned his intentions just a few years ago.

He’s silenced those who believed his career in IndyCar would be a one-and-done. His commitment cannot be called into question. He’s become not only one of the series’ fiercest competitors, but one of its most persistent spokespeople. He’s among the series’ most active on social media, constantly promoting IndyCar and defending it from those who attack it.

He also spent much off his offseason starring on a reality TV show where he regularly found himself outside his comfort zone. While there were surely plenty of fun aspects of running around with Conor Daly on “The Amazing Race,” that much time in the spotlight isn’t exactly a dream scenario for a self-described introvert.

And remember, Rossi and Daly were almost always wearing IndyCar gear while on the show. Neither of them had to do that. IndyCar asked, of course, but they weren’t contractually obligated. Sure, it’s a small gesture, but think about how far Rossi has come in three years.

From a person who, for most of his life, had never considered IndyCar to one who voluntarily put himself through some personal anguish -- belly dancing on national TV, not his favorite -- to promote it.

“I feel it’s my responsibility — not only as someone who won the 500 but as one of the young American drivers — to try and bring new eyeballs to the sport,” Rossi told IndyStar earlier this year. “It’s a big, daunting task, and we’re not even close to accomplishing it, but we’re taking steps in the right direction. And I’m doing everything I can in what I feel is my duty to try and grow the awareness for the future.”

His hard work has paid off in the acquisition of a legion of loyal fans, who cheer for him and his #BabyGirl every week. It’s also gone a long way in the paddock.

***

While some wanted to cast Rossi as a villain earlier this season following a few headline-making scrapes with Robert Wickens, that’s simply not who he is, Hinchcliffe said. While it’s taken others a long time to learn that, Hinchcliffe figured it out pretty quickly.

Following that 2016 season-opener in St. Pete, Hinchcliffe and Rossi became fast friends.

After spending nearly a decade driving in Europe, the only driver Rossi knew very well upon returning to the United States was Conor Daly, and at the time, Daly was living with Hinchcliffe. At one point, Rossi lived with Hinchcliffe, too, so he was around a lot, the Canadian driver said with a laugh.

Insider:Arguing with myself: Why Dixon, no Rossi ... will win IndyCar championship

More:Spencer Pigot to return to Ed Carpenter Racing

“We got to know each other pretty well during that time,” Hinchcliffe chuckled. “I got to know who he really is and what he’s really like. Not just what comes across on track or on TV or whatever. ... I remember, he used to say he’ll train at PitFit, but he never wants to train with other drivers. Now we all go in at 8:30 in the morning, and if we’re not there, he’ll be like, ‘Where’s Robbie today? Or where’s James today?’ It helped bring him out of his shell a bit. He’s a really funny guy. He’s a really intelligent guy. He is pretty intense and introverted with new people, but at the core, he’s a great driver and a great friend.”

Zach Veach, one of the paddock’s friendliest faces and Rossi’s teammate at Andretti, echoed Hinchcliffe’s remarks. Veach has raved about working with Rossi this year, extolling his virtues as both a friend and mentor.

Kanaan eventually came around, too. It took some time, and it also took Rossi getting him in a room he couldn’t escape. Or as Rossi might call it: his home turf.

Almost two years ago, Rossi, Dixon and Kanaan ventured to Las Vegas for an IndyCar promotional appearance. Kanaan still wasn’t very fond of his young companion at the time, but he had no choice but to get to know him a little better when the three of them were locked in an Escape Room together. Escape Rooms, for those who don’t know, are like live-action puzzles. People go to them to see if they can piece together clues to find their way out.

Rossi is famously fascinated by Escape Rooms having successful navigated his way out of dozens of them. Perhaps being in his element allowed him to come out of his shell a bit.

“We spent an hour in that room, and that was it,” Kanaan said. “I learned a little more about him, and since then, man, to be honest, we get along really well. We make fun of each other all of the time.

“I walk by, and he’ll go, ‘Remember when you used to hate me.’ And I say, ‘Oh yeah, I really used to hate you.’ And we laugh. To be honest, he has grown a lot in the series. The first year he came and won the 500, nobody had any idea who he was. I think people thought he didn’t appreciate the win. I don’t think that’s the case. I just think people don’t know him.”

Regardless of what Kanaan, Hinchcliffe or anyone else say about him, Rossi’s icy demeanor will always rub some people the wrong way. To some, his sharp wit will always comes across as cheeky or disrespectful. And he’s never going to be everyone’s friend with his take-no-prisoner, elbows out attitude on track. But that’s who Rossi is. Unapologetically. Does that make him a villain?

Rossi hopes not, but he can’t worry too much about it. He has IndyCar races to win, championships to fight for. If fans or other drivers don't like him, that's fine. Just as long as they know how happy he is to be where he is.

“I love this championship and everything it represents," he said of IndyCar. "I feel very fortunate to have the opportunity to be here. I wouldn’t want to have it any other way.”

Follow IndyStar Motor Sports Insider Jim Ayello on Twitter and Facebook: @jimayello.