[Her reply isn’t immediate, one because Pepper is thinking out her answer, and two because she’s creating a filter for this conversation. Although she intends to be vague as Vastra is a stranger, she still wants that additional privacy.]

He’d changed. [Which is obvious, because what sort of person wouldn’t change at all in a year?] I think it was for the better, but—sometimes I feel like there are things I still don’t understand.

[Secrets kept, likely in an effort to protect her.] That’s what makes it hard; knowing I missed an entire year of his life.