[The mention of Leviathan giving out trials peaks his curiosity, and he wants to ask more about that, but the lure of hearing about the Calamity Selves has a stronger pull. As Takeshi begins speaking about them, Riku nudges his plate onto the table and sits forward, his arms balancing on his knees. A captive audience.

Hearing them being described as being similar to the darkness of the heart is uncomfortable knowledge, but not surprising. How many times had his own darkness arisen to remind him of all the things about himself that he didn't want to admit? How many times had Xehanort's Heartless tried to manipulate him by using his weaknesses against him?]

So the only way to be free of the Calamity Selves is to admit to the things you've been trying to hide? It sounds like the crystallization only delayed the inevitable.

[The mention of Sora brings his mind to a halt. Particularly the part about him being the one who gave Takeshi those scars. He stares at them in half bemusement, half horror. If there is anyone who could successfully fight off the darkness in his heart, he would expect it to be Sora.]

...Sora became a pawn? Sora?

[It's going to take some time for him to wrap his head around this one. But when Takeshi mentions volunteering he knows that it's the best opportunity to get at what he really wants to know.]

What was it like...facing your Calamity Self?