[Iskandar remembers the sign so he just nods. He considers her a friend. Isn't it obvious he'll come to her aid whenever she'll need it? If only it would be in his power to help her. Yet still it's nice to feel appreciated.

That offer though ....]

I...wouldn't...couldn't...never...I...

[To be that totally at loss for words is a rare occurrence for usually eloquent King of Conquerors. He feels it's a generous offer and rejecting it off hand would just be ... it wouldn't sit right. Still he can't accept it either! Just can't.
First, she's already shinki of Caster. That's clear as daylight. Only this fact alone would make it at least breach of trust. Outright treason at worst. It would be as if he kidnapped a member of his family. Willingly or not, it would be Iskandar who would be in the wrong. Caster would have full right to enact his vengeance on him and Iskandar would never even think to blame him for it at all.
Second, shouldn't naming your shinki be less casual? It was for him. μὰ τὸν Δία! He has it depicted on the walls of his temple! It was a major event. This bond is not something you should ever treat this lightly! (Congratulations! You've unlocked embarassed Iskandar mode. He's cursing in Greek now.)

Then he realizes there could be one other explanation. Is she in trouble? They all seemed to get along well with Caster. Or do they? Did HE do something inappropriate?]

Are you having trouble with your god? Does he treat you well? Do you need me to go talk to him?

(...and full big brother Iskandar mode for a good measure...)