"Okay, Master the book will tell me what you got. Let's see you are now a Phoenix Slayer."
"But aren't Phoenix immortal?"
"Yes and no. While a Phoenix can be reborn every time it dies. They choose when they don't want to be reborn." Said Igneel.
"I guess that means I have to be proficient enough or find a Pheonix that doesn't want to be reborn. Okay, you can go know Sayla."
"See you later master." With that, she was gone in a poof.
"Natsu we should go to bed if you want to be able to train in both slaying methods. Also, your head needs to heal from this much thought."
"Okay WAIT WHAT DO YOU MEAN FROM THIS MUCH THOUGHT."
"Whatever you think come on."
"Phff... Okay."
The next morning.
"Okay, Natsu you know how I said it would be hard for you to learn another slaying method. Well since you got the Phoenix slaying the moves are pretty much the same with different words except for the first since they don't have any. The only challenge for you will be their healing techniques but once you learn these you will be even more resistant to any sickness or poison."
"Dad, what are the other difference between dragon slayers and Phoenix slayers?"
"Dragon slaying magic is a lot more destructive than Phoenix slaying magic. Also, dragon fire is a lot hotter than what any Phoenix can produce. Phoenix Magic does not have any special modes however they can teleport but the ability is hard to learn. Now I think that was enough information let's start training."
"Okay, dad." With that, he started the same warmup as yesterday but not dropping the boulder today. Then a thousand pushup, squats, situps, burpees, and an hour plank. After that Igneel thought Natsu how to read and write in draconic. Then Natsu would train in the basic moves of dragon slaying. Then he would learn dragon culture. This schedule continued for a year with some differences like learning to read and write in English and learn human culture instead of draconic.
"Okay, Natsu now that you have learned the basic moves I now want you to try work on phenix healing magic somehow."
"Don't worry dad I know how to train my healing magic."
"Really how?"
"The basic information is in my head somehow."
"Okay since it looks like that won't take you long I want you to work on the dragonslayer secret moves."
"Hey, dad how many dragon slayers secret moves are there?"
"There can be an indefinite amount of moves. Secret moves are moves that you create and aren't the basic moves. That's the reason they're called secret moves because only you know them. However, I will give you two that I created. They are called exploding fist and lava plum. The exploding fist is explanatory. Lava plum on the other is where you stop on the ground and make lava come out of the ground. Now you have to work out how I did those and recreate the move and other new moves. Now, do you see what I mean by indefinite?"
"Yes, I think."
"Well, at least you can think."
"HEYYYYY."
"But on a serious note Natsu I forgot to mention don't create moves that cost too much magic or constantly use special moves. The drain on your core could kill you or have negative effects for you that even the Phoenix magic your trying to learn won't help you recover."
With that, Natsu trained for nine months mostly learning Phoenix magic after blowing himself up form trying to learn secret arts. Even if he could now think he still just the same old Natsu.
"Okay Natsy since you said the information isn't coming to your head anymore I'm going to assume that you learned all the healing magic you can. Now the next step for you to work on would be Dragonforce the power to match that of a full grown if used properly. However, there is something you should know. Using the Dragonforce will speed up your prosses of being a Dragon."
"Wait! So I'm turning into a dragon right now and how do I stop it?"
"Yes you are being turned into a dragon but it's a very slow process but using Dragonforce will speed that up exponentially. The way to stop it is for me to go into your body and release something that Grandeeney said. Don't bother asking me what it was because I don't remember. I think I fell asleep halfway through her boring explanation."
"So when were you going to go in my body?"
"In five years when you are around twelve. Now Natsu I wasn't supposed to tell you anything but since I'm this far in I might as well tell you. I and four other dragons are going to send you and their slayers to the future by 400 years. When we do that we will be inside your to help deal with the strain and when we get to the future the earth will be overflowing with Ethernano. With this overflow, we can gain parts of our souls back and help speed the process of preventing you from becoming a dragon."
"Why don't you have your soul?"
"It was stolen by a dragon that was once a dragon slayer by the name of Achnalogia. That is what I and the other dragons are trying to prevent. If you are taught Dragon slayer magic by a dragon you will turn into one. However, if you learn dragon slayer magic any other way you will not. We don't know why that is but we are trying to prevent it from happening to you."
"Okay, I guess I get it so what were you going to teach me?"
"I was going to teach you fire dragon king mode. A mode, more powerful than dragon force however the mode will have a far greater strain than that of dragon force. Are you ready?"
"But wait if it's the fire dragon king mode won't that speed it the process more than the dragon force?"
"No fire dragon king mode is just raw power while Dragonforce makes you take characteristics of a dragon. do you see what I'm getting at."
"Okay, I get it now."
"Now get back to training."
With that Natsu trained to handle the strain and to use fire dragon king mode in two years.
"Okay, Natsu since I don't have anything to teach you anymore call your demon for another type of slayer ability."
Natsu then had summoned Sayla.
"Hellow master the book has glowed meaning you can now have another slaying ability."
"Okay, can you now open my book?"
"Yes master, Okay let's see you now have the ability to slay the gods themselves."
"So a fire god slayer hmm. Okay then Sayla, before I forget I will be gone for 403 years, don't worry if you don't hear from me. Other than that you can go."
"Okay, master."
with that Sayla was gone and Igneel immediately began to help Natsu train in the art of god slaying. this training went on for the remainder of the time they had together. Natsu went to bed with Igneel next to him. the next morning all that was left was a note and a white scally scarf.
Notes: Natsu training might seem fast but with him thinking more quickly I fell like he could have completed all the training Igneel had for him. Wendy is younger than Natsu by a couple of years but her training seemed more compete than his. The cannon Natsu is pretty dumped yet he learned a majority of everything except for dragon culture/ history. So I feel the amount of time he spent on it is appropriate. Also, Natsu won't use his god slayer abilities unless he has to. that being said dragon force and dragon king mode will be his very last resorts if he can't beat his opponent.