LOS ANGELES -- Taran Killam’s excitement reached a fever pitch near the end of the third quarter.

It wasn’t just that the defense was dominating or that the offense was flowing or that his beloved Los Angeles Rams were riding a 27-point lead over the division-rival Arizona Cardinals with less than 20 minutes remaining. It was that they were doing it all without Greg Zuerlein, their All-Pro kicker, a circumstance that forced them to attempt two-point conversions at inopportune times and even prompted their punter, Johnny Hekker, to try a couple of field goals.

Killam, the actor and comedian of “Saturday Night Live” fame, expressed his unbridled joy the only way he knows how. He grabbed the smartphone out of his shorts, turned it toward his face and screamed into it from the top of his lungs on this searing Sunday afternoon.

“They have no kickeeeeeeer!” Killam proclaimed, instantly capturing the attention of everybody around him. A poor, unsuspecting middle-aged man made his way down the aisle with a tray of food, and Killam wrapped his left arm around him to make his point again.

“They have no kickeeeeeeer!”

Killam is Jebidiah Atkinson, the overly harsh 19th-century newspaper critic. He’s Mokiki, that mysterious drifter who does “The Sloppy Swish” in the middle of Manhattan. He’s the creepy Merryville Brother, the Brad Pitt impersonator, the overly protective brother obsessed with the word “glice.” He was King George III in “Hamilton.”

And he is, in real life, an exceedingly passionate, fully invested, die-hard Rams fan. That’s the persona that is starting to stick.

Killam went on “Jimmy Kimmel Live!” last week in a Rams blazer to celebrate the start of the season, then appeared on “The Rich Eisen Show” in full-on Rams gear, from the jacket to the cap to the self-made T-shirt that read “Gurley Hungry.” But none of that topped the light-up, Rams-themed Christmas sweater that he wore on “Late Night with Seth Meyers” in December 2016, while his favorite team was in a free-fall.

In the spring, Killam hosted the Rams’ pre-draft roundtable from the rooftop of a swanky hotel in downtown Los Angeles, interviewing players and talking unscripted about the team for more than an hour. Those are his Rams bona fides. Throughout the upcoming fall and winter, his Instagram page will once again become littered with selfie videos of himself screaming -- sometimes incoherently -- from his seat in the lower section of Los Angeles Memorial Coliseum.

Taran Killam mixes it up with his fellow Rams fans at the tailgate before the home-opener. Gail Fisher for ESPN

Eliot Schwartz, a friend from college, is asked what it’s like to watch a game with Killam.

“I’m gonna say this, and I mean it in the most loving way possible -- sometimes it’s embarrassing,” he said.

Killam likes to call football his “Rosebud,” a phrase that harkened the central character in “Citizen Kane” back to the innocence of youth.

Killam grew up in Big Bear, California, and lived next door to a family of avid San Francisco 49ers fans. Sundays became a celebrated day of gathering, one that Killam hoped to someday replicate in adulthood. He left his childhood home at 16, his parents separated five years later, and along the way Killam found himself longing for those Rockwellian portrayals of American wholesomeness. Football would become his vessel.

As he neared his 20s, Killam vowed to adopt whichever NFL team came to L.A. first and follow it ardently.

It just so happened to be the Rams, a franchise with deep-rooted history in the marketplace.

“It genuinely is the most selfish thing I’ve ever done,” Killam said. “You can ask my wife [Cobie Smulders]. ‘I’m going to buy these season tickets, and I’m going to dedicate myself to this team and this tradition, of following them and getting to know the players and supporting them through thick and thin because it satisfies some sort of nostalgic desire in me.’ And she was like, ‘OK, how much do season tickets cost?’ ‘Well, it’s the stadium seat licenses you really have to worry about.’”

It’s the home opener, and Killam is wearing a snug-fitting throwback jersey of his favorite player, Aaron Donald. On his head is a blue and yellow Rams cap with horns on the side, and on his feet are Rams-colored Nikes that he went online to design himself.

Joining him are Schwartz; Ronnie Kimble, a friend from high school; and former SNL cast member Paul Brittain. They are three parts of a 10-person group that rotates use of Killam’s three additional season tickets. As Kimble said, “We all sub out who gets to go with Dad.”

Some are fans of other teams, some are generally apathetic toward football, and some have adopted the Rams through sheer force of will from Killam, who last Christmas gifted five of them with personalized Rams jerseys, his way of saying “this is your life now.”

“It was an obligation gift,” Killam said. “Fully an obligation gift.”

They packed into Killam’s SUV a little after 11 a.m. PT on Sunday and drove east, from Venice to L.A. proper, and the Los Angeles Chargers came up in conversation.

Killam has an analogy for their awkward move from San Diego.

“It’s like they still haven’t fully broken up with their ex, and their ex still lives next door,” Killam said. “It’s like they just moved into the front yard of the duplex, and their ex can still hear them through the wall.”

Killam never misses a home game. Gail Fisher for ESPN

Killam spent $60,000 on two stadium seat licenses for the opulent venue that the Rams will share with the Chargers in Inglewood, California, by 2020. He longs for the day when he can valet his car, walk into one of the lounges on the club level and have a cocktail waiting on him before kickoff. In the meantime, he loads a small cooler with homemade guacamole, parks in Lot 4 and does his best to mimic a tailgater.

Killam is very nervous about the Rams’ Sept. 27 game against the Minnesota Vikings, a highlight of the Thursday Night Football package. He’s nervous about the opponent, but he’s also nervous about missing it.

That Monday, Killam will be in New York for the premier of his new movie, “Night School,” which he co-stars in alongside Kevin Hart. Two days later, back in L.A., is the premier for his new sitcom, “Single Parents,” which airs Wednesdays at 9:30 p.m. ET on ABC. All that means is that he can’t really get out of shooting for the show that Thursday, which makes him think he might not be able to make it to the game until the second half. The thought consumes him.

“That’s the game,” Killam said.

But this, the home opener, is the only game that matters now. In a span of three hours, Killam will scream into his phone about Todd Gurley’s “power,” repeatedly profess his admiration for Donald and shout at Andrew Whitworth -- “I love you Big Whit!” -- while the towering left tackle makes his way to the locker room for halftime.

He will do an impression of head coach Sean McVay describing his admiration for "Teenage Mutant Ninja Turtles" sensei Master Splinter and note how Brandin Cooks, the Rams’ diminutive primary receiver, looks like Mysterio from “Spiderman” with his oversized helmet.

He will lament the injury to Obo Okoronkwo, an unheralded fifth-round pick, praise undrafted journeyman JoJo Natson, who now returns punts, and never miss an opportunity to answer the question “Whose house?” with a hearty “Rams' house!”

Killam’s 9-year-old daughter, Shaelyn Cado, has taken full advantage of that, using it as a way to tug at her father’s heart after misbehaving. She did so recently, after ripping open a bag of flour and watching it spread all over the living room floor. Killam was noticeably upset, so she went to her room, put on a Gurley jersey, came back and asked, solemnly, “Whose house?”

Killam had no chance.

“It’s happened like half a dozen times now,” he said. “I cry every time.”

At home, Killam has nearly 10 Rams caps (including the one celebrating their division title last year, which he will not wear until the Rams win the NFC West again). He owns at least five jerseys -- and will soon buy one with a Robert Woods name and number -- to go along with a handful of sweaters and jackets.

But as the fourth quarter begins, Killam heads to the merchandise store for more gear. He picks up a bucket hat, a pair of socks and another cap, all in blue and yellow. He spots some Rams board shorts -- “that’s fun” -- and grabs a football he hopes to someday get signed by all the players.

When the Rams moved to L.A. in 2016, Killam flew across the country to witness every home game and always stayed until the bitter end, even on days when the score got out of hand.

“I was looking forward to sucking for a while, because I feel like that’s how you earn your stripes,” Killam said. “That’s how you become a real fan.”

It didn’t happen that way. The Rams hired McVay -- “a cyborg” in Killam’s mind -- and underwent one of the greatest turnarounds in NFL history last season. They’re a star-laden Super Bowl contender now, and Killam is among the most passionate members of a fan base that is still growing slowly.

A team trying to re-establish its identity in a city got an avid follower in a celebrity trying to re-establish an identity with his fandom.

It works.

“My hope,” Killam said, “is that 30, 40 years from now, when my children are grown up, and they have children of their own, going to the game with Grandpa is something to look forward to.”