That's an inner voice that all the member's of this family might hear and some point, always at the most inconvenient moments, ruining any of chance at happiness. Five's inner angry voice sound like Reginald and to this day he can't get over the fact the man had been right about their argument about time travel. Nothing but his own hubris got him stuck in the future.

But thinking about that won't help him and it sure won't make Klaus feel better. The other boy doesn't sound very convincing with that 'I guess'. but the rest seems to get to him. Five allows himself to smile, in the privacy of his bed no one else but Klaus can see it after all.

"Would I lie? I don't go around complimenting people without a good reason, and that was amazing."