thoughts on what might be in store for Juliette
I wonder if whatever is happening to Juliette, courtesy of Adalind and her "Vial of Wrath," is going to lead to a storyline where Monroe steps in to help her learn control, and that kind of life-altering self-discipline we know he's gotten himself to. (And for the record, I don't think we're looking at a situation where Juliette is becoming a Wesen; nothing we've been shown so far suggests that such a thing is possible. Only the hexenbeists have been shown capable of being "unmade," and my guess is they're something entirely unnatural.)
I'm thinking something like this would achieve several ends at once: Monroe started out as a sort of mentor for Nick, but Nick, while he's still learning, is much more steady on his feet in this world now, and he and Monroe have evolved to equals and friends. Putting Monroe in a mentor role to Juliette would let them continue to show his character in that light, which I think he's great in, but it makes it something fresh and new from Monroe and Nick's relationship. It would also provide a very natural window to the story of Monroe's past, which we know at some point they're going to delve into. They could make some more in-depth revelations there, get into what Monroe used to be into and what made him change.
On Juliette's side of things, it would be a way to do what people have been wanting to see: bring her into the Grimm world in a believable way, without dropping her into a position that's *too* close to Nick's role in the action, and it would give her a story independent of Nick's that explores her as a character and is still very relevent to the non-human, supernatural happenings. It makes her the novice to all of this, but it would be a very different story from what Nick's initiation was.
I also suspect that however things play out, there will be a period where Nick and Juliette are separated next season, and I think establishing this kind of relationship would create both great tension (Monroe being a close, crucial figure to both Nick and Juliette, but in that awkward position of seeing them parted and doing that balancing act), *and* keep a sort of connection or overlapping of ripples there that could lead towards a reconciliation.