Year 1518
Diesel just turned eighteen he also reached twenty feet in height but he feels hes done growing taller, 'all that's left is to fill out this amazing body I have now with more muscle. I'm truly thankful I dont have chicken legs like those pussys back on earth that skipped leg day. Or worse look like Don Chinjao with short skinny legs and a huge torso.' Diesel thought. 'Its finally time.'
He walked to the center of a large area he had cleared off and turn to look at his best friend, "Fenrir this may get violent as I will most likely be in a lot of pain at first and may not be in my right mind. No matter what happens DO NOT under any circumstances touch the fire I'll be putting out as it can burn even the soul. Now stand back."
Fenrir looked concerned but did as he was told to anyway after seeing how cautious Diesel was being and retreated to the edge of his observations range to watch over his friend.
"This is prolly gonna hurt like hell.... Whatever I've never been afraid of pain. No pain no gain right? Bring it on!" he snarled and reached down deep to pull on the power dormant within himself. For a moment nothing happened. But then.
Diesel started to burn seemly from the inside out. It started with his face and quickly spread across his whole body but he didn't make a sound. He just grit his teeth and held fast to his mind as he refused to let the rider control him even though he didn't even know if that would be a problem here. It was better to be safe than sorry as Johnathan Blaze lost control when he transformed.
He burned for what felt like an eternity but he was sure it was only around fifteen seconds or so. Finally it was over and there stood the ghost rider in all his glory, Diesel was in full control and started shadow boxing to see what had changed.
He noticed his body when transformed had gained a respectable increase in strength, speed, stamina, and durability. He could tell the animal hide clothes he was wearing were currently far more durable than before and he could feel that he was able to use his hellfire to make basically anything a weapon. He expected all these things so that didn't surprise him, but the way his observation haki changed did.
He was able to see Sister Vannesas soul a decade ago so he knew he could do that when he fully awoke, but now he could both see souls and hear them. This basically allowed him to read minds and tell when someone is lying. He wasn't expecting this but it will definitely be useful given how good some people are at hiding their true nature and help root out Cipher Pol spies later on.
He had never had a chance to fight another person so he wasn't one hundred percent sure when he guessed what level Fenrir and himself were at, but he was pretty sure that when transformed he would be a match for Sengoku or Garp. Just a few days before this he figured out how to use future sight and he was now able to coat his fist with the aura of haki. Although it wasn't perfect he was confident he would have ryuo mastered when he left in a year.
He was going to spend the next year getting to understand his devil fruits limits, finish mastering ryuo, and hopefully finish mastering future sight. Combine that with his ability to read minds and his physical capacity it would make him damn near unstoppable even in the new world. He'd definitely be on par with Garp and Sengoku, the only ones he'd have to be cautious around are the four emperors.
He decided that he needs to find a way to mask his presence so even people like Garp dont realize how strong he is. He wasn't sure how he was gonna do it though so he'd just do his best and ask Silvers Rayleigh when he get to Sabaody. He may not help him but it's worth a shot as he seemed like a decent dude.
As he was contemplating and planning for the future he "heard" Fenrirs anxiousness, and called him over with a gravelly voice to show him he was ok. After that he ran around touching stuff to make sure he wouldn't burn Fenrir when he touched him.
He found that the flames he put off only burnt what he wanted them to unless he caught something on fire then threw it away from him it kept burning and spreading. 'I'll have to be careful with this or I might burn down a whole island by accident' he thought. This fire was like evil napalm on crack and if left unchecked could cause total destruction to an area.
Not to mention Hellfire can literally burn your soul so even if he hadn't learned haki he still would be able to deal with logias if he was able to roast them with his fire for a bit. That said he wasn't currently able to project any of the hell fire away from him, he knew the quantity he put out wouldn't ever be anything on par with the flame flame fruit but he should be able project at least a small amount after his ability gets stronger.
He was really excited when thinking about getting a ship and bike later on. However he didn't wanna imbue just any ship he came across as he wasn't sure if he could make an unlimited number of mystical vehicles, he seriously doubted it. So he figured they'd just hop around on merchant ships while they were still in the blues and hitch a ride on a marine ship to get to the grandline as hes sure they'll owe him some favors.
Before all that he still has a year left to train so hes got to get back to work.