Meanwhile, we finally get an explanation about Chas' immortality, and it's an immensely satisfying one: He technically isn't immortal after all. Two years ago, when Constantine was concerned that Chas was too drunk to drive home from a concert, he casually cast a protective spell he'd picked up from Arthurian texts - if the subject is struck down, they will absorb the life force from others around them. But the spell backfires when the concert stage actually catches fire, killing Chas along with over 40 other people. That's a lot of souls to absorb, giving Chase one extra life for every individual death. It also partly explains why Chas follows Constantine without question, since he feels responsible for snatching souls away from their rightful place.
Not only is that a great explanation that fits with Felix's soul-stealing plot (which does come up), it's a great example of how Constantine's version of magic should work. It's not about being a powerful Level 20 magician, it's about spells that work so literally they can have unintended consequences. This theme has come up occasionally in past episodes and really helps Constantine stand out from other magic shows.
The rest of the episode is jam-packed with so many impressive twists and details, that if I took the time to detail everything here, you could have watched the whole episode - few other shows casually drop in demon hunting and botched seances that are otherwise unconnected to the plot. But perhaps the nicest touch is that compared to last year, John Constantine is really becoming an asshole. That's a good thing - the show pulls a lot of punches regarding the dark acts John is capable of, but here we finally get a sense that he doesn't care who gets burned in his quest. (In one case, literally.) Other noteworthy moments include manipulating Chas' guilt to keep him around as a partner, and being made to realize that his approach with Felix was wrong (but never apologizing for it). Hellblazer's tone is finally shining through the network television cracks, and I for one couldn't be happier.
Not that the episode is without its flaws. Mark Margolis plays Felix as an appropriately campy Level 20 black magician, but we never actually see his lowly magician stage to provide a better context. (And given how the episode ends, we probably never will.) But Zed is once again the mixed bag. Her relationship with John is far more natural than before, and they can actually flirt and banter without feeling forced. Sadly, she still doesn't have much to do other than play the psychic plot advancement card. Even a big moment, like finally explaining her complicated backstory to John, ends up being so brief and muted that it doesn't have much importance. And why, exactly, is Zed blaming John for last episode's cultist break-in when she ignored his advice and led them to the front door? Come on, let's blame Constantine for something terrible he actually did.
But in the end, these quibbles are well balanced by everything the episode gets right. The episode is fast-paced, jam packed with supernatural twists, and ends in a satisfying way for everyone involved. What's more, Constantine's happily lighting cigarettes and smoking in our faces without a care. All is well with the world.
Bottom Line: "Quid Pro Quo" is all about what Constantine does best: Throwing seemingly unrelated magical twists at us, and watching John survive them by the skin of his teeth. Toss in DC Comics' villain Felix Faust, a satisfying explanation for Chas' immortality, and a blatant disregard for network smoking regulations, and Constantine feels like its preparing to end the season on a high note.
Recommendation: Anybody else getting the feeling they'll miss this show when it's gone? "Quid Pro Quo" is part of the reason why.