Possible they hid their presence by developing their human forms as far as I remember Acnologia can't just sense dragons from anywhere on the planet so it's possible he overlooked them
I get what you're saying but it's not good. It hasn't been
good since the 100 years quest was first explained. I tell you this in good faith, not for the sake of being hateful towards the series.
Think of what this all does to Acnologia as a character. He was the guy who "1 vs everyoned" all dragons and hunt down any survivors.
Regarding whether or not he could "find" the dragon gods, we at least know he can pinpoint dragons from a big distance:
- It's how he found God Serena.
- After killing God Serena, he gave an exact count of the remaining dragons (slayers).
- After finding out about Irene being a dragon slayer, Acnologia was teleported to the most distant extreme of Fiore and ran straight to her (took him a while to arrive, though).
Him not having killed dragon slayers earlier is easily excusable. They hadn't been around for centuries, so he wasn't expecting them to pop out of nowhere and it took him some years to act. It's the opposite with the dragon gods. In Irene's case, he didn't know she was a dragon slayer until he faced her, but that can be attributed to her enchantments. Her whole human form was not a transformation like Acnologia's or Ignia's but magic faking her humanity.
The exceptions to "all the dragons in the world becoming extinct centuries ago" were all easily explainable. The same reasonings, however, don't work on the dragon gods, whose power levels only make matter worse. If guys
that powerful could hide from him, nothing is stopping the author from further killing Acnologia's mythos by suddenly revealing there were thousands of dragons surviving in small communities around the world. Of course, Mashima, as an author, can just write that and justify it as "they were just hiding", and "it would be what it is", but it would be bad. In fact, taking into account that Suzaku's master (forgot the name) actually hunted dragons, this may very well be the case in this sequel.
Gildarts ran into Acnologia literally on that same continent, so at least we know for sure he wasn't always "far away on the planet". Acnologia chilled on a continent with active dragons that the humans of the continent knew about and even hunted them, but he did nothing about them or about the dragon slayers doing the hunting.
Just see how easily each of these dragon gods was found by our main characters. Literally no effort for the most part. Remember Acnologia had literal centuries for this, before they started building the labyrinth and putting this plan into action and sealing their powers, and they were "Acnologia-level", Acnologia was around. Did they, instead, reach Acnologia's level after they went into hiding? If so, how exactly did their power grow while actively hiding? How did Mercphobia even "hide" when he was passively releasing his power daily? Selene can be excused because she could travel between dimensions.
Then you have Elefseria: Elefseria was a dragon slayer running a guild called "Magia Dragon" right next to the dragon gods. Acnologia never found out about the guy? He was very renowned and the dragon gods all knew about him. Why didn't Acnologia? He created the first guild in history, with a dragon theme and name, and with a single quest about hunting dragons. He even sent out quest invitations to guilds of all the continents.
There's too many reasons why Acnologia should have looked into it all.
It's messy, and it's not good that the reader has to think up flawed excuses for the author because he gave none. Even with your answer, Acnologia comes off as inefficient and lazy at best and a coward at worst. Last chapter restored
some of his hype regarding his power, at least, since the sequel had also previously murdered that. Before the sequel, he only came off as an extremely efficient and lethal beast.
It's not like the original series was "great" since the Tower of Heaven arc but it was better than this.
This was just setting the stage for what's to come
That's the meta explanation. There's no in-story explanation. I get why Mashima wanted this, what I don't get is why
the characters chose this.
Each had their objective in front of them, it's against eachother's interest to let the other person cook:
- Ignia knows nothing about Zeref 2 and what she can do, he should be intimidated enough that she has Acnologia's powers and that he didn't even know she existed. The worst he could do is let her go.But then again, it's Zeref 2 who ran away, so it's her reasons we should look into.
- Zeref 2 believes to be stronger than Ignia and wants to fight him. The minions being around are irrelevant, they're for sure tiers below the two. She could have won everything she desires just by fighting Ignia and killing him right there. Instead, she chose to retreat and gather Oración 6 3.0 because the story needs a long arc and a group of enemies for the minor protagonists to fight. Ignia has just showed up he's always had aces under his belt to power up and is going to create and army, clearly an inconvenience for Zeref 2's objectives (and why she will now need her minions... but she wouldn't if she had just won right then and there).
It's not a smart move, which is why I wondered about an
actual explanation. Why did she even go to confront him and reveal her existence and her intentions to destroy him, even flexing that "he's scared of her power" just to walk away? Why go in the first place? "The arc needs to happen" is not an explanation for the character's motivations.
I follow FT because I like the characters but I would unironically rank FT's writing as the worst one in shonen history that I can remember after Boruto. Boku no Hero and Reborn are not far behind.