While things are calm, now might be a good time to consider what Dahlia mentioned about Alide not being on our side forever. So, I decided to look back through the things she's said for any hints.
"when we disappear... Well that's a fun question. We go home. We have delightful homes in the tower. You will actually be able to visit us in our homes on the last floor. Though... that is assuming you make it to the last floor,"
This is an early line I found, way back on the third floor. This probably means if Alide is supposed to turn against us as part of her role, it will likely be on the ninth floor.
"Alide picks up the ring and looks it over, interestingly not seemingly taking any damage from it, "Hmm... Ring of Clear Mind... Warded against the Tower Below and above. The Ward is not intrinsic, but was added specifically..." she mumbles to herself and then smiles and places down the ring,"
She seems to know the circumstances behind the Ring of Clear Mind, but didn't tell us. This likely involves the aspects of her role she doesn't want us to know about. And the ring may be a handy countermeasure should we end up facing her.
""As for the floor monster... Harvester. Honestly if you're going to lose to a floor monster, they're not a bad choice. Definitely some of the more fun you can have losing, but oh boy will they mess you up if you do," she says and a gentle smile appears on her face, seemingly remembering some fond memory, "of course I imagine you'd prefer not to lose. Which means... I guess I can try to help you out."
This line has struck me as odd ever since we found out Harvester eats souls. My thought on first reading was 'oh Harvester does something Alide thinks is hot, and maybe Alide has actually done it with Harvester' but the whole soul sucking thing, and something I'll get into below, make me think that isn't the case. Instead, I wonder: Could Alide be someone who eats souls as well?
""As for the Harvester... She would have raped you, she's a succubus. A specifically powerful one, but otherwise just a Succubus. She would have attempted to as her name suggests harvest your soul... through your vagina. Also don't fall for the whole 'let's play' act. She's not a child, she's a sadistic homicidal monster who likes to act coy while describing the horrible things she intends to do. While you probably could have come to an arrangement with her, and she likely wouldn't have actually sucked the entirety of your soul out of you it would be very one sided and you would not have come out of it well. Killing her was the best option. A fact that is true of all the floor monsters," Alide says and there's an edge to her voice. Clearly there's something of note between her and the floor monsters, but it doesn't seem likely she'll be forthcoming with that information."
Again, doesn't seem like Alide is into getting her soul sucked out. Could she be something beyond a succubus? That, and the fact that she has some sort of animosity towards the floor monsters. Given she can avoid them by popping out as soon as they show up, they don't pose any danger to her. So where does this animosity come from?
I think, with a couple more clues, we could unravel the mystery of Alide that Dahlia mentioned.