The letter Shunsui receives in return is plain in most ways; plain paper, plain writing, plain speech... sort of like he was uncertain of how to approach a proper reply.
Kyouraku-san,
I'm doing fine, all things considered. I'm surprised that you remember me. I wasn't aware that you were here, to be completely honest.
You don't need to apologize about that. I have something of a temper, I'll admit, and Ichigo is very important to me, but I shouldn't have reacted like that to you. I know you were only trying to warn us and prepare us for what could happen.
I don't think it's necessary to try and make it up to me; you didn't do anything out of line. I appreciate the offer, though. I hope everything is going well for you, as well.
/o/