Behold! This is the exception.

Sunday promises to bring us that rare occasion when animosity between professional sports teams meets or exceeds that of their respective fan bases. Because no matter how much fans of the New England Patriots might despise the Indianapolis Colts, and vice versa, it seems clear that the franchises themselves carry a deep-seated and personal disgust spawned from years of on- and off-field sparring at all levels.

"The rivalry," former Colts general manager Bill Polian said this week on ESPN, "is real."

The NFL is a for-profit business. Everyone makes money. Cash, business partnerships and itinerant employees all take the edge off competitive emotions. So why do these particular millionaires -- and two billionaires, owners Bob Kraft (Patriots) and Jim Irsay (Colts) -- hate each other? As we prepare for Sunday's matchup at Lucas Oil Stadium, let's take a trip down memory lane:

1. The Colts started Deflategate

Few had heard, and almost no one cared, about air pressure of footballs before Colts general manager Ryan Grigson forwarded an "FYI" email to the NFL office on Jan. 17. The note advanced a theory from Colts equipment manager Sean Sullivan that the Patriots were breaking league rules by deflating footballs to give quarterback Tom Brady an advantage.

In his spare time between watching film of aging running backs, Grigson wrote: "All the Indianapolis Colts want is a completely level playing field."

When Colts officials grew suspicious about football inflation during the AFC Championship Game, according to the Wells report, it was Grigson who burst into the NFL's command center to press the issue. Without Grigson's tip, most of us still wouldn't have heard -- or cared -- about football air pressure.

2. Déjà vu for the Colts

Why were the Colts so sensitive to something that, by all accounts, would have been a minor instance of cheating? As it turns out, they were among the apparent victims of the Patriots' previous cheating scandal as well.

According to ESPN The Magazine, former Patriots video assistant Matt Walsh told congressional investigators that he had been instructed to take video of the Colts' offensive signals as well as the hand movements of then-quarterback Peyton Manning.

The NFL later issued $750,000 in fines and docked the Patriots a first-round draft choice for defying its video rules in what became known as "Spygate." During the time period when the Patriots are alleged to have illegally taped opponents, they won seven of 10 matchups against the Colts.

Tony Dungy was harsh in his criticism of the New England Patriots after the Spygate scandal. Brian Spurlock/USA TODAY Sports

3. Tony Dungy -- Tony Dungy! -- took shots

Typically reserved and nonconfrontational, Dungy stepped out of character and enraged the Patriots with public comments about Spygate in 2007. "Really a sad day for the NFL," Dungy said when the NFL's discipline was announced. "It's another case of the 99 percent good things that are happening being overshadowed by the 1 percent bad."

That sanctimonious tone probably played a role in an icy postgame handshake between Dungy and Bill Belichick after the Patriots' 24-20 victory in Week 9 of that season.

Dungy didn't let up, either. In February 2008, during an interview about an NFL video game, Dungy joked that "we'll probably only let New England have cheat codes."

4. Polian was angry, too

In an interview with ESPN The Magazine, Polian -- now an ESPN analyst -- revealed that he opposed the NFL's decision to destroy the evidence it accumulated in its Spygate investigation.

"I wish the evidence had not been destroyed because at least we would know what had been done," Polian said. "Lack of specificity just leads to speculation, and that serves no one's purpose -- the Patriots included."

5. Polian had been angry for a while

The Colts and Patriots met in the AFC Championship Game four seasons prior to Spygate, on Jan. 18, 2004. In that matchup, the Patriots limited the Colts' high-octane offense to a pair of touchdowns in a 24-14 victory. Led by Polian, the Colts were livid with the Patriots' defensive strategy.

Belichick's defensive backs "rerouted" Colts receivers whenever possible, a euphemism for pushing them early in routes to disrupt their timing. As it does now, the NFL had penalties on its books for illegal contact (hitting receivers more than 5 yards downfield) and defensive holding (grabbing jerseys), but referee Walt Coleman -- as was common in those days -- did not enforce them.

That following spring, the league's competition committee issued a point-of-emphasis memo. Its topic? Illegal contact and defensive holding. Polian was the committee co-chair.

6. Perhaps Belichick's biggest failure happened in Indianapolis

With a six-point lead late in the fourth quarter of a 2009 game, Belichick decided not to punt from his own 28-yard line on fourth-and-2. When Brady's pass to running back Kevin Faulk came up short, the Colts gained possession just 29 yards away from the go-ahead score. (Belichick couldn't challenge the spot because they were out of timeouts.)

Manning's ensuing touchdown pass to Reggie Wayne lifted the Colts to a 35-34 victory in a game that began a stretch of three Patriots losses in four games.

Dungy couldn't restrain his glee. By then a television broadcaster for NBC, he said Belichick's call was so bad that, had it happened while playing a video game, the opponent would have said: "Come on, play for real."

Tom Brady has beaten the Colts four times out of five chances in the postseason. AP Photo/ Charles Krupa

7. Brady mythmaking at Colts' expense

Fans have debated the merits of Brady versus Manning (and successor Andrew Luck) for more than a decade. The best argument for Brady, of course, is his four Super Bowl victories in six appearances. Manning has won one, while Luck hasn't made an appearance.

Three of Brady's four championships came after eliminating the Colts in the playoffs. And according to Jacob Nitzberg of ESPN Stats & Information, Brady has a 62.8 Total Quarterback Rating in five total playoff games against the Colts. The QBR of Manning/Luck in those games is 34.1.

8. Patriots have poured it on post-Manning

Neither Belichick nor any of his players have publicly expressed disdain for the Colts, but their actions have spoken for them in recent years.

The teams have played four times since Manning last wore a Colts uniform. The Patriots have hit at least 40 points in each game and outscored the Colts by an average of 29 points.

That group includes a 59-24 romp in 2012 during which the Patriots padded a 21-point lead with three fourth-quarter touchdowns. Brady did not leave the game until the Patriots' final possession. There have been only 20 games in NFL history in which a team has scored more points than the Patriots did that day.

9. The Vinatieri "coup"

The Colts were thrilled in 2006 when they signed place-kicker Adam Vinatieri -- the hero of the Patriots' victories in Super Bowls XXXVI and XXXVIII -- to a massive free-agent deal. Vinatieri was part of the Colts' championship team that season, and at 42 is still one of the league's top kickers. But the Patriots hardly missed a beat.

In his 10th season, successor Stephen Gostkowski is arguably the best kicker in the NFL. He owns the league record for consecutive extra-point conversions and has converted 94.3 percent of his field goal attempts (83-of-88) since the start of the 2013 season.

10. Feelings are hurt

The cumulative effect of this rivalry seems clear. The Colts feel cheated and the Patriots feel targeted for their high achievement. You won't hear them say it in so many words, but let's allow two local columnists to do it for them.

This week, Gregg Doyel of the Indianapolis Star wrote that the Colts don't "play, coach or cheat" as well as the Patriots. Doyel added: "The Patriots cheated the team in my city. Residents of Indianapolis and the surrounding areas, you give the Colts the best you've got: money, emotion, more. The Patriots rigged the AFC title game. Cheated the Colts. Cheated you."

Longtime Boston columnist Jackie MacMullan, writing for ESPN.com, had this to say: "The Patriots are on to Indianapolis, and no matter what they say -- or, more to the point, what they don't say -- they have been waiting months for this. And somebody is going to pay."