[He looked down at the mention of Sozin. He had many complicated feelings stemming from this topic. But it was pretty clear. That's how Roku found out.]

I see. I'm... sorry, Roku, that you had to find out like that. [He leans out of his chair to give a brief hug before sitting back down.] Katara... got you out, too? She really is so brave. [Especially when he considers her issues with Firebenders.]