It's best to start this slice of Jake Arrieta lore with a minor discrepancy; it was either a couch or an overstuffed chair.

The exact piece of furniture isn't essential, what Arrieta did with it and why, that's the point here. The fact that its identity is in dispute, however, is fitting.

Because it's also impossible to perfectly define Arrieta, who Friday will become the youngest pitcher to start Opening Day for the Orioles since Mike Mussina in 1994.

Is the 26-year-old right-hander arrogant or confident? Is he serious, intense and self-absorbed or goofy, fun-loving and big-hearted? Those who view him from afar observe one Arrieta. Those close experience another.

"I think a lot of people see the arrogant side of him or think they see that," said Orioles' lefty Zach Britton. "But, really, he is just a confident guy. And when you get to know him, he is one of the best buddies you can have. He really is there for you whenever you need him."

When he is comfortable, Arrieta can be goofy, confident and competitive all at once. Case in point: The couch/chair story.

This much isn't disputed: Arrieta and his best college pal,St. Louis Cardinalsinfielder Matt Carpenter, were in a friend's living room two years ago before a TCU football game.

They were playfully arguing about who was stronger, with the 6-foot-3, 200-pound Carpenter needling the 6-foot-4, 225-pound Arrieta, who took matters into his own hands. Literally.

"I was joking around, saying I am way stronger than you," Carpenter said. "And then Jake just picks up the couch in the room and starts doing squats with this couch over his head. I'm like, 'This guy is unbelievable.'"

Arrieta laughs at the memory, pointing out that it was actually a sturdy smoking chair, maybe 3 ½ by 4 feet and he and Carpenter made it a competition. If Arrieta remembers correctly, he lifted it 15 times — until his wife yelled at him to put it down.

Classic Arrieta. Challenge him. Tell him he can't do something. Suggest he is inferior.

Then get out of his way as he attempts to prove you wrong.

"I think there are a lot of things that motivate me, but to put it into a few words: I think it is just wanting to be better than I can be," Arrieta said. "Whatever it might be — ping pong, jumping rope, lifting weights, running or whatever — if you can continue to strive and work better than you are capable of being, you are never going to be complacent or satisfied. And that's just the way I am."

"His own breed of person"

That's the way Arrieta has always been, and Lou Arrieta has the pictures to prove it. Arrieta's father saw evidence of his son's intensity the first year he coached him.

"When he started playing T-ball, I took a couple pictures of him swinging the bat at 4 years old. And you can actually see the determination and the 'I-want-to-be-as-competitive-as-possible' look on his face. And he was only 4 years old," Lou Arrieta said. "Whether it was riding go-karts or home-run derby in practices … He always wanted to be No. 1."

Name the stage of his life, and there are examples of that Arrieta competitive fire.

"Any recreational sport, he could win two out of three, but if the third game I won, he'd want a rematch," said Trey Curtis, Arrieta's best friend from high school in Plano, Texas. "He'll say, 'I want a rematch. We are going to play again. It's a fluke you won.' He always has to get the last win, and he won't leave until he does."

Troy Patton, the Orioles' lefty reliever and Arrieta's best buddy on the team, says they compete in nearly everything.