There’s nothing I dislike more than when a rule is set up in a book and then it’s broken. This is in regards to style and in content. Let me explain.
Thoughts are often done one of three ways. One way is to use italics, one is to use single or double quotations, and one is to use a comma followed by ‘the character thought.’ I prefer single quotations myself, although I have used italics at times. That said, in a single story or novel, you cannot switch from italics meaning inner dialogue to quotations. It’s jarring for the reader. That said, I also dislike when italics are used for inner dialogue and for emphasis as well. Personally, I rarely ever use italics for emphasis. I think the reader can decide where to place importance, although I don’t mind when other authors do this. Point being, if you’re setting up a grammatical rule for yourself, don’t change it part way through your story. Keep it consistent.
Worse, though, is when a rule is set up in the world and then it’s broken. The first time I became aware of this was actually in the first Batman movie with Michael Keaton. It was set up as a realistic world where Batman needed wires to swing on and followed the rules of physics. Fine. Then right at the climax he and Vicki Vale drop dozens of storeys and then the wire they’re on goes taut, and he isn’t squished in his suit. It would be the same as hitting the ground at that point, but they didn’t die. Even as a young Batman fan I didn’t buy it.
Then the third Batman movie came out and in the first scene Val Kilmer leaps off the top of a building and lands in his car. He, too, would certainly be dead, but the world was being set up far more like a comic book than the real world, and it worked. I went with it, even though it was very similar to the fall Michael Keaton had in his movie, but the rules were set up so that it would be possible. The first movie wasn’t, so it didn’t work for me.
Oddly enough, the third movie ended with a similar scene (apparently movie directors think that falling quickly after someone is really exciting) and they made sure that there was flex in the wired, which kind of wasn’t needed. Weird.
So if you set up a world where some miraculous event saves the day, you need to ensure that it’s possible from the beginning. You need to make sure that the world supports it, otherwise, it feels like the author just couldn’t figure out a plausible way to solve the problem and relied on something that couldn’t
Any way you look at it, grammatical or plot-wise, be consistent.