[bladeofdarkness]

Originally Posted by TheDisruptiveOne

Kallen's feelings have to be pretty strong to accuse him of using geass to bend her heart to his will. What that means is that Lelouch was basically in her mind non-stop during the year of their separation.

Spoiler for Episode 18:

So Sayoko is going to apparently save Kallen right before her execution.

This might possibly be the lie that Lelouch gives her.

Kallen: Why did you save me, Lelouch?

Lelouch: I needed your strength for the battle.

Something like that would be a pretty good way of hurting Kallen's feelings.

if sayoko tells her something else during the rescue (leluoch-sama told me to get you to safety , he was quite insistent that you saftey be made the highest priority)
it might clue her in that its a lie