Seeing Mab in her goofy and capricious mode like this always makes me feel as if there's going to be a major serious shoe dropping soon.
It's not hard to imagine how awkward it would be to have Mab hanging around. Yes, it's nice to have something as powerful as a Fae hanging around as a protector, but as Alexi says "What happens if she gets mad?" The few times we have seen a truly angry Mab, the consequences have been disturbing to say the least.
Speak of the Devil and... Mab would likely show up wearing a devil costume thinking it's Halloween and expecting free candy despite the fact she can just will it into existence with magic and- ...where was I going with this?
Well, Mab has already made it clear to Pyro that there's a big difference between "Friend" and friend of a Friend's sister.