I can hardly believe that your mind has... [But then he remembers the Valeyard. And also a faint memories of something a bit frightening in the Doctor's mind before he was booted violently out of it.]

Well, I suppose we all have a few shadows we'd rather weren't there. [Sometimes still he wonders how much Pandora's genetic legacy influences his actions.]

All right. I'll accept that it might not be an entirely hopeless cause. And don't worry, Doctor, I'm sure that if your shadows should start to bite...your brother will save you. If he's not busy examining Martian sculpture, that is. [He's certainly not going to admit out loud that he'd help. But the sentiment's there.]