The Dark Power : Those who lost and the one who won
The Dark Power wasn't supposed to infect Kyouya.
First, Kyouya has all this arc with the Wolf Canyon that differentiate him from Hikaru and Tsubasa. And the Dark Power doesn't overwhelm him as he does with Hikaru, Tsubasa and Ryuuga.
And those aren't the only differences. Let's take a look at two other points showing the difference in Hikaru's, Tsubasa's and Kyouya's reaction, and consequently on Dark Power's influence on them.
Psychological influence
The Dark Power, and Ryuuga, uses a psychological ascendancy to win. Their power impress, or even scare their opponents. If it's not enough, however, Ryuuga doesn't hesitate to use words to make their opponents doubt about themselves.
Hikaru loses even before the duel's beginning.
"Why did I- Why did I think I could ever win for a moment… against a guy like that?"
-Hikaru, episode 41
Thought Tsubasa resists longer than Hikaru, using the strategy he planned to battle Ryuuga, he loses before the battle's end.
Ryuuga: What's wrong? If you think you can dodge it, give it a try. If you think you can stop it then go ahead and stop it. Why don't you?
Tsubasa: Don't quit Eagle.
Ryuuga: I congratulate you for being able to make me use some of my real strenght. As a reward, I'll take extra special care and stealing that power from you. (...) It's finished. You were reckless and foolish to even consider challenging me in a battle at all.
Ryuuga: So say hello to the pit of despair!
-episode 45
Tsubasa lets Ryuuga's words (and power) touch him without replying. At the end of their duel, he's entirely passive.
On the other hand, we have Kyouya. He is evenly matched with Ryuuga, driving him to give up the Dark Power for their duel and even snatching some kind of compliment from Ryuuga:
"You are no match for me. (…) However, I can't remember anyone taking so many of my direct hits without completely collapsing. I give you credit for that."
Kyouya fights Ryuuga as if he was any other blader (an interesting blader, not a horrible monster he has to defeat to protect the world). He returns every blow and taunt, without being impressed, and even less scared, by Ryuuga. When L-Drago's Dark Power intervenes, Kyouya isn't afraid…
Ryuuga: Ah what?
While Ryuuga is shocked by the Dark Power's apparition. This is the first time he shows such an expression.
Kyouya is destabilized, somewhat worried for Ryuuga, but he isn't afraid.
Kyouya: Ryuuga? What's wrong? (…) Yeah. Just when I thought it was getting good. Now the circus' act is becoming a bit much, huh? Hey Ryuuga?
He tries reaching out to Ryuuga but the Dark Power entirely overwhelms him. It soliloquizes about its need and Kyouya's answer is just:
"Okay, that's really nice. Go ahead, and try. But I'll never let you steal from me my blader's spirit. (then, thinking) Ginga, take a good look. This is my blader's spirit."
Kyouya stays in fighting mode until the end of their battle. The last sentence he says is adressed to Leone, "Shatter him! Let's use everything that we've got left!"
If Kyouya loses the duel, he isn't the one who loses against the Dark Power. Ryuuga is. The Dark Power controls him as a puppet at the end of the battle.
A symbolic detail
Hikaru and Tsubasa fall. Kyouya doesn't. He's standing despite his defeat, which is shown from different angles. He never hits the ground.
