While Fairy Tail may be criticized for its generic nature and fan service, to those who actually give the series the time of day (for several days), the world of wizards and dragons is one of the most consistent and endearing out there. Though the story's engagement has never ceased since its debut, that doesn't mean that some criticisms aren't warranted.
Look no further than the series' fill-in for Bardock, Minato Namikaze, and Monkey D. Dragon, i.e. the legendary father figure. "The Fire Dragon King" Igneel is Natsu Dragneel's adopted father and one of the most hyped figures in the series' history. While one can never be disappointed with a big, fire-breathing dragon, a lot of Igneel's arc left a lot to the imagination...and not in a creative way. Though his run was short and sparing, Igneel's legacy left a lot more questions than answers.
10 Hiding Within Natsu
One of the most glaring issues with Igneel and possibly most of Fairy Tail's late game is the infamous "400 Year Plan." This refers to the remaining dragons hiding away for a few millennia so that they can hide from Acnologia and heal. The self-proclaimed "Dragon King" did give them a run for their money during their first encounter, and it just makes sense that they'd want to heal a little.
What doesn't make sense, however, is the exact places they decided to take refuge. Much like the other dragons, Igneel decided that the safest place to be was within the bodies of their Dragon Slayer students. Dragons could have hidden anywhere else on the planet and still survived Acnologia's wrath, yet Igneel had to hide behind (or within) his own son.
9 Creating Dragon Antibodies
Hiding and healing, however, weren't the only reasons why Igneel and co. chose to hide within their students, and they certainly weren't the worst. In addition to mooching off their students' body cavities, the dragons chose to hide within them so that they could also prevent them from corrupting and turning into demented dragons like Acnologia.
To do so, they apparently produced "antibodies" that prevented the kids from becoming dragons. For those who didn't read that correctly, Igneel produced dragon antibodies, because that's a common power within dragon lore. It's almost as reasonable as Midichlorians.
8 Time Traveling For Ethernano
Stepping away from the absurdity of dragon science, let's look at a much easier and less controversial topic within fiction: time travel. In addition to hiding within their students, the dragons of old decided to hop into a DeLorean and travel to a far off year. They did this to make their healing and power-ups easier. Their original time was apparently low on ethernano, Fairy Tail's equivalent to chakra, nen, and batteries.
In order to stand a chance against Acnologia, Igneel needed to travel to a future plentiful in ethernano so that he could heal up and be prepared for his revenge. The hole in this logic, however, is the fact that Acnologia himself would also have access to more ethernano. There is no advantage here that outweighs Acnologia's. It's just a lateral move.
7 Dragon Soul Technique
For those who were a little confused as to how Igneel managed to hide within his ward, here's the logic behind it. In addition to being big and breathing elements, Igneel and the other dragons also have something called "Dragon Soul Technique," a unique and really specific power that lets them hide within the soul of another person.
Besides being way too situational (this power is never explained or used for any other purpose), it also shouldn't be possible within the context of the story. Using the Dragon Soul Technique requires the dragons themselves using their souls, but Acnologia earlier supposedly reaped their souls. While the meaning of a soul is a fickle thing, one can assume that Igneel shouldn't be able to use a "Soul Technique" without a soul.
6 Loving Humans
The other dragons have described Igneel as having loved humans more than anyone else. While Igneel has certainly shared some solidarity with humans and fought alongside them, there really isn't a lot of evidence to suggest that Igneel actually loves humans, at least, more so than the other dragons.
Igneel definitely had a "warm" affection for Natsu, but that's it. He didn't really have a kind word or opinion on humans besides that. Considering how nice Grandeeney turned out to be, Igneel probably shouldn't rank that high on the human ally list.
5 Leaving Humans Alone
Despite the statement above, Igneel certainly couldn't keep his hands off of human affairs. This is despite earlier claims in the series, in which, Igneel proclaimed that the dragons shouldn't get involved with the humans.
While his actions mostly hold up with this, Igneel has clearly shown some flexibility towards Natsu. During times of crisis, Igneel risks his anonymity a bit to give Natsu some encouraging words and advice. Though minimal, this is arguably interfering with humans.
4 Never Saving Fairy Tail
With that being said, why didn't Igneel interfere just a little more? While it's encouraging to see a proud father trust in his son's abilities, Igneel's help would've been very much warranted during several of Fairy Tail's key crises. Natsu and his friends have been at death's door multiple times against the likes of rogue wizards, giant demons, and interdimensional cat people.
Assuming that he cares about Natsu or, at least, needs him to survive/hide, Igneel could have saved a lot of heartache and offered a helping dragon claw on multiple occasions. That would be loving humans more than anyone else.
3 Using "Dragon Slayer Magic"
Dragon Slayer Magic was invented as a means of counteracting the dragons during a time of hostility. It came from some of the more charitable dragons who shared their secrets to benefit humans. While this is certainly a pivotal move, one has to wonder why the dragons themselves call their own magic "Dragon Slayer Magic."
It makes sense when another species uses it to kill dragons. It doesn't make as much sense when used by the dragons themselves. Wouldn't it just be elemental magic or, well, just magic to them? Why is Igneel a master of "Fire Dragon Slayer Magic" and not just fire magic?
2 Telepathy
While on the note of powers that dragons don't typically have, Igneel is also an affluent user of telepathy. This is how Igneel has been able to communicate with Natsu throughout the story as well as how he presumably talked with the other dragons. If not, his first appearance alongside Grandeeney sparks so many more questions.
Assuming that using this power doesn't give away his own location, Igneel probably could've used this more often to communicate with the rest of Fairy, offering them helpful advice, insight, and other news. At the very least, it's strange that he never taught this to Natsu. Things would've been much easier if Natsu was more than just a pyro.
1 Never Mentioning Ignia
Last but not least, let's touch on the unexpected plot twist that Hiro Mashima totally didn't make up for a sequel. In addition to being an amazing adoptive father towards Natsu, Igneel was also apparently an absentee father towards his own, biological son, Ignia. This isn't to say that Igneel's circumstances weren't trying, but he never once thought to mention his other son, not even to his clearly favorite son.
Given that Natsu's arc early on was to find Igneel, the story would have been a lot spicier if he was also looking for his adopted brother. Igneel also clearly had a telepathic connection with the other dragons, begging the question as to why he didn't at least try to contact or sense Ignia. Considering how powerful Ignia became, he probably could've been a huge help in the fight.