[ Kamui thought back to that time. If his eyes were starting to change it was probably because he was tapping into his vampiric powers.

He remembered how he tempted to bite the ninja, and that probably was the reason they started to change. But he wasn't going to tell Itachi that.]

...They change with intense emotion.

[That was the truth, whenever he was ticked off, his eyes were the first to change.]

I try to appear as normal as possible, usually. But sometimes I drop my guise when I'm angered, or something similar.