Saïx is not hugely attached to the "meaning" of being a Knight with the whole thing about assisting the heroes and being there to support them, but he does appreciate people working and being productive. So being able to provide incentive for that, to make others work for their achievements, is something he finds pretty satisfying overall. Ultimately his goal is not to aid the Heroes or fight off the Darkness or rebuild Aather--it's to regain his and Lea's memories, and if he has to do all the other stuff to achieve that goal, then that's fine. He's okay with doing that, and he'll do it without complaint*, but he doesn't have a specific attachment to it.

*relatively. Saïx complains a lot just by habit, but it's rare that he actually means any of it. Also, characters who greatly dislike complacency is now a ping of mine...

What's the most unexpected thing that's happened with playing Itachi in Aather?