Leslie appears in Part 11 (with backstory).
Oh, yeah. There we go. In my defense, even though it was only two parts previous, that was a year and a half ago
Edit: I notice checking back in the last few issues, I see Charlotte left H with Jane and Thena last issue, but now she seems to start back with him picking up where she left off just before that bit in issue 12, telling him his new fantasy. Gave me pause in the re-read, but I assume we're just flashing back to it now because it's more relevant.