Tonight the Saints play their biggest game ever, and Manning wants them to lose because his son is the quarterback of the Indianapolis Colts.

Big joke by the Great Scorekeeper in the Sky, no?

Truly, this is an unbelievable set of circumstances. This would be like Bobby Orr rooting against the Bruins in the Stanley Cup finals because his son skates for the San Jose Sharks. Imagine if Red Auerbach had a son who wound up playing against the Celtics in the NBA Finals?

You bleed into a team for four decades. You live in the city for 39 years. You help rebuild the city after a horrific natural disaster. Then when the long-suffering local team finally gets to the Promised Land, you pray for defeat.

The reason is simple. Blood is thicker. It’s a universal truth. Ask Mike Pagliarulo’s dad what it was like to raise a boy in Medford, then find yourself rooting against the Red Sox when he came to town as third baseman of the New York Yankees.

Archie Manning makes no apologies for his loyalties today. He said that anybody who doesn’t understand would have to be a person who never had children.

He’s right about that one. Watching your kids play ball is one of the great joys of life. It can be agonizing, but the emotional energy is indisputable. It can blind you to reality and turn rational people into maniacs. It can be consuming. It’s much harder than playing ball yourself. Archie Manning knows this.

Tigers manager Jim Leyland once told me that he was far more nervous watching his son play Little League than he was managing in the World Series.

Two weeks ago, I went to Conte Forum to see the Boston College women’s team play Virginia in an ACC basketball game. Scott Brown was at the game to watch his talented daughter, Ayla. He’d just returned to the Hub from his first trip to Congress as a Senator-elect.

I went over to say hello at halftime. This was less than 48 hours after Brown shocked the nation with his upset victory and he was signing autographs and posing for photos. I greeted him by congratulating him on his victory and was startled to find him in a cranky mood. All he could talk about was the game.

Then I remembered. Ayla hadn’t played a strong first half. She was scoreless and struggling. And in that moment, Scott Brown - king of all the political world - was just another frustrated dad, wondering what was going on down on the court. He was in the moment and the moment wasn’t good because his daughter wasn’t playing up to expectations (for the record, Ayla scored 9 points in the second half, but BC lost a close one).

A lot of great things are happening for Scott Brown, but the BC women’s season will be over soon and Ayla is a senior, and that means he doesn’t have many nights left as the dad in the stands. After 15 years of hovering in the gym, it’s going to be a big downer for the high-flying senator.

Which brings us back to Archie Manning, the dad who gets to watch two of his sons play in three Super Bowls over a four-year period. What must that be like?

“I’m a blessed guy,’’ Archie told the Globe’s Albert Breer a couple of weeks ago.

He was not blessed when he played for the Saints. He played for seven head coaches in 11 seasons and the best record was 8-8. He was quarterback of the 1-15 Saints who inspired the bags on the heads of fans (the “Aints’’). His oldest son, Cooper, asked Archie’s wife for permission to boo.

“I can’t remember wearing those [bags],’’ Peyton Manning said this week. “I was too young.

“Cooper and I used to, while waiting on my dad, used to go out on the Superdome turf and play. Get a big ball of tape, wad it up, and play one-on-one, 100-yard football. The first person to score twice, you are pretty much exhausted after that.

“My dad would always come out and get us on the field and take a little time to be with us. He would always sign his autographs for all fans after the games. Most of these times after tough losses.’’

Archie and Olivia Manning raised their three boys in a two-story Greek Revival on First Street in the Garden District. The boys starred in football, basketball, and baseball at Isidore Newman School. Archie was in the stands for just about every game.

The Mannings evacuated to Oxford, Miss., when Katrina struck, then came home and contributed to the rebuilding of New Orleans. Archie fought to keep the Sugar Bowl in the Superdome.

Today the Saints go for the ultimate win, and the guy best-equipped to stop them is the little boy who played on the Superdome floor with the wadded-up ball of tape. And the patriarch of the first family of New Orleans will be cheering for the Indianapolis Colts.

It’s only natural.

Dan Shaughnessy is a Globe columnist. He can be reached at dshaughnessy@globe.com.