Obito was deeply curious about the current Kakashi, but also worried and a little excited. He saw hope in Kakashi of replacing Madara Uchiha, though that also made him worry about Nagato's situation. More than anything, he wondered how Kakashi had managed to use a Sharingan that originally wasn't his as naturally as Obito did, without any burden at all. In the past, even briefly using the Sharingan had been more than Kakashi's body could bear, and that had only been a three-tomoe Sharingan, not the Mangekyō Sharingan he had now.
Yet now, Kakashi used the Mangekyō Sharingan as effortlessly as he did, as though Kakashi had been the eye's owner all along. There was no strain whatsoever, and even the side effects had vanished. That was what intrigued Obito most.
As Obito fought Kakashi, he thought, How did Kakashi do it? If I knew, I could just transplant Nagato's Rinnegan into myself. I wouldn't need to rely on that old bastard Madara Uchiha's power at all. I could unleash the Rinnegan's full power myself, and the chances of successfully casting Infinite Tsukuyomi would rise considerably. But how did he do it? Looks like I'll have to find a way to uncover Kakashi's secret. That's what I'll do.
During their fight, Kakashi noticed that Obito seemed distracted. He immediately thought, Hmm, what is Obito plotting? I'd better be careful, or I might fall into his trap. Still, he has the nerve to let his mind wander while fighting me. I'll have to teach him a lesson.
Kakashi deliberately feinted, and the distracted Obito took the bait. Forming hand seals, he called out, "Fire Release: Great Fireball Technique!" Seeing Obito attack just as he had expected, Kakashi smiled faintly and formed his own hand seals. "Earth Style: Earth-Style Rampart!"
The earth