Akaya expects more snark in Jae-ha's response. He's pushing buttons on purpose, itching for a fight. He wants to hit him where it hurts, because he has a deeply buried fear that nothing he does could affect Jae-ha in the way he wants it to. After all, if Akaya mattered to him, then why would he have stayed away for all these years?

"What makes you think you're useful now?" What's this 'brother Akaya deserved' look like? It might sound like a bitchy rhetorical question. But the messed up thing is, he might actually be expecting an answer to this.