You know it's not going to be a good day when the sky cracks open and a giant dragon arm reaches through. By that point it just sort of feels like the par for the course when the glowing tentacles come down for the lovely young girl of the group, because as the folktale says, it can always be worse. Fortunately for us (and Wendy!), this is Fairy Tail and Lucy has just finished rewriting Natsu into a Real Boy, so even if she, Gray, and Happy still don't know it, things are almost definitely going to work out.
How are the two scenes related? The answer is a simple “Acnologia.” Anna miscalculated when she forced him into the time rift, and it turns out that he ingested the thing, granting himself time magic powers while also separating body and soul. Now his dragon body is free to wreak havoc on Fiore (starting with Magnolia, because that place is a trouble magnet) while his spirit collects dragon slayers inside what was once the time rift in an effort to stabilize his new magic. So when Natsu vanished, it wasn't because Lucy misused a semi-colon, it was because Acnologia snatched him up along with all the others with dragon slayer magic. Not that she's aware of the fact for most of the episode; we get plenty of Sad Lucy scenes interspersed with more exciting fare, but we viewers can rest assured that not only did her rewrite work, it also very likely gave Natsu the extra oomph he'll need after the fight with Zeref.
The use of those sad scenes is actually part of this episode's problem. We're very near to the end of the story at this point, and while elements of the manga's finale definitely felt rushed, the anime may be gearing up to drag those same pieces out a bit too long. We do know that some anime-original material about Acnologia's past is coming up, which may do a lot to ease that stretched-out feeling, but this episode definitely isn't doing quite enough to keep the momentum going. Part of the issue may be the lack of smooth transitions between scenes; the whole thing feels very disjointed as it moves between Lucy and Gray, the group in the water, and Acnologia's cozy new home in the former rift. There are places where things could have led more smoothly into each other, and less Sad Lucy might have helped to keep the action from stalling as well. As it stands, however, there's just an awkward quality to the way that the story is divided up, and that hurts the flow of the narrative.
We also see a return of some of the persistent animation issues from episodes past. Most striking to me was the fact that the ocean around Fiore must be extra salty and free of movement, because everyone is absolutely still in the water, which looks like it may only be about chest-deep on most of the characters. Yes, animating everyone bobbing in the waves and/or treading water would have been a pain, but with the storytelling issues also present this week, it really stands out that there's no movement to the sea or the people.
Fortunately, we also get some of what has kept Fairy Tail feeling like a cohesive story all along – the presence of the theme that friends and family are of the utmost importance. When Natsu is the only one able to move in Acnologia's realm, we assume that it's because he got there last and hadn't been put into a crystal pillar yet. But as his friends manage to break free of theirs, they say that they could do so because they heard the voices of their loved ones – something Natsu may have been hearing in the back of his mind all along, because Lucy, Gray, and Happy were certainly distraught by his sudden disappearance. Their power, in other words, comes not just from themselves, but from their friends' belief in them and love for them, and that may turn out to be the key to defeating Acnologia once and for all. As far as we know, after all, he doesn't have any such people to help him out.
That's something I hope to see expanded upon in the final few episodes. It was integral to the resolution of Zeref's story, so it would be nice if the show could do the same for Acnologia and make him into something more than a one-note villain. Fairy Tail has a fairly good track record for its anime-original material, so I'm feeling tentatively hopeful as we head into the final episodes.
Fairy Tail: Final Season is currently streaming on Crunchyroll.