I was still thinking about the odd break Harley had in Harley Quinn and Power Girl #5. When the Harvester of Sorrow unlocked her "inner Joker", though I'm still unclear on what that meant.
When Harley was introduced in Batman: The Animated Series, and developed over the course of her experiences there, she was a tragic character. She'd fallen for a guy who didn't regard her as anything other than an occasional amusing distraction from his real interests, and she couldn't turn away from him. The longer she was around him, the more she seemed to realize that Mistah J's interests were not really her interests - even their goals with regards to crime aren't the same - but it didn't matter. Harley could go off by herself, but if she got too close to the Joker, it was like he had a gravitational pull and just drew her back in to his orbit, and his plans.
Now, that's no longer the case. I don't know how, but Harley's finally realized that relationship was a disaster for her, and seems committed to staying away from him. Some of that may simply be that the Joker's mostly been confined to Snyder/Capullo's Batman title, but there's been no indication Harley is wistful or yearning for the clown to return to her. She's not looking for him, inquiring about him, committing crimes to honor him, nothing. This is good. Even if Harley is still prone to destruction and antics, she's at least trying to direct that energy in productive ways (in her own book, at any rate).
But that doesn't mean whatever trauma she experienced with the Joker didn't happen, and that's what the comic reminded me of. Harley's tried to distance herself, tried to take her circumstance and make something for herself out of it, and she's done a good job. But that ugly past is still there, the destructive and cruel tactics and worldview the Joker would encourage, are still something she's learned, or had imprinted on her, and it may only take a sufficiently traumatic experience to bring it out.
I don't know if Conner, Gray, and Palmiotti were commenting on the fact that psychological trauma is not something that just magically goes away, as it is sometimes portrayed in fiction. That one can be doing well for months, maybe years, and then they have a bad day and it comes crashing back on them. If they were, they undercut it by the fact she came out of it a few minutes later like it was a fugue state, and didn't seem to suffer any ill effects, which doesn't seem like something that normally happens. But it did catch my attention.