Five more years have passed and Diesel now stands eighteen feet tall with a much more muscular frame than before. Both him and Fenrir have gotten even stronger over the past few years of training. Fenrir has mastered armament haki and had just unlocked observation while Diesel has figured out how to control his conquerors haki.
Unfortunately he hasn't got ryuo or future sight mastered, he can feel hes missing something but hes not sure what. 'Must be nice to have plot armor that makes this shit way easier' Diesel muttered. 'If memory serves based on the manga luffy figured all this out within three years while I've been at it for ten with observation and eight for armament. That said physically speaking I should be just a little stronger, faster and have more stamina than fourth gear luffy at the start of the Wano arc.
'Considering that's just my normal strength without using the power of the Rider and he has to use haki the entire time he is in fourth gear....
But at that point he'll learn ryuo... I think after balancing everything out, I should be more or less on par with him after he learns ryuo, as I am right now' thought Diesel.
This revelation greatly irradiated Diesel as hes been using haki right at a decade now and a kid is going to accomplish more with it in two and half years than he has in ten. Hes already forgotten that Luffy had a master teach him, and that he accomplished basically the same level of strength as a nineteenth year old MC with plot armor, at fifteen. He should be able to take on Admirals as he is now but has decided to wait to leave the forest till Ace leaves home in four years.
Diesel is hoping to be at Garps level and have Fenrir close enough to kill an Admiral in an even fight before he leaves the forest. He didn't want to mess with the timeline more than neccessary but as the Spirit of Vengeance (and because he just likes to fight) he felt he needed to clean up the seas before he went to the grand line. So he was going to hunt down everyone with a bounty at or above one million in the North, South, and West blues. He'll leave the east alone as it might change something and its supposed to be the weakest sea anyway.
Diesel knew he needed money and influence and the quickest way he could think of to attain it was to become the best bounty hunter in the world. When he eventually gets there he could have the greatest scientist of this world, Vegapunk, design and build him a ship, motorcycle, and a sawed off lever action shotgun for his size. After all the Rider has to look as badass as he is right?
During the past few years Fenrir somehow completely fused with his devil fruit, making it so he was always in his transformed state even while sleeping. Diesel didn't know this could happen but guessed that a zoan could have this effect if the same kind of animal as the zoan ate it.
Like for instance if a lion ate the lion zoan fruit or in Fenrirs case if a wolf ate a wolf zoan of some kind. Then they would just mesh and resonate so well with each other that they had actually became that animal instead of just being able to transform into it. Fenrir now had ridiculously tough hide and was seriously durable, Diesel doubted anyone below Rear Admiral would even be able to scratch him. Everything about his physic was over the top and completely ridiculous, there was also some weird kind of destructive force that he noticed every time he ate something.
Diesel didn't know for sure if this had any benefits other than not having to actively transform but, it seemed like Fenrir got more talented, grew faster, and had better instincts after he ate the fruit. All of this put together made Diesel think he knew what devil fruit Fenrir ate as there was only one beast that fit all that criteria. 'I wonder if I really have been blessed with good luck' thought Diesel.
Since the Admirals are notorious for having neglected the haki part of their training instead focusing on their devil fruit, by the time they leave in four years Fenrir should be strong enough to kill an Admiral if need be. His training for the next four years are gonna be geared toward mastering observation more than anything else as it will be used the most.
'He can learn ryuo after he masters future sight' thought Diesel. Not realizing how ridiculous his thinking was as only a select few are able to master it even on the grandline. He wouldn't care even if someone told him as anyone who would be a part of his crew would have to learn haki because it leaves you vulnerable if you dont know it in the new world.
While he wasn't going to actively look for a crew, he might take in a few people he liked later on. Now that he thought about it he'd be more apt to take in more animals which made him laugh but eventually he'd have to take on disciples. He was still a master martial artist after all he just hadn't had a chance to fight any humans since he came to this world so he couldn't showcase what he was truly capable of.
After all martial arts are designed specifically to deal with other humans so they only really shine when fighting a humanoid enemy. After watching the show Diesel believes this world doesnt really have any "real" martial artists. In his mind the rokushiki are closer to body arts like for instance tekkai, it's only purpose is to make the body denser and therefore harder to damage but it has to be combined with a fighting style to be used. Shigan is literally just tensing up your finger and shoving it into someone when you get to the core of it. Kami-e is just making your body super flexible making it easier to dodge. Fishman karate is the only one he has knowledge of, and of its users the only one of note so far is Jinbei.
Now he doesnt mean that they aren't useful, he even plans on learning the rokushiki and Fishman karate. It's just that he has a feeling that in terms of technique hes going to be far above everyone other than a few of the swordsman. The rest of the powerful people he saw on the show were basically just the equivalent of experienced street fighters, using brute force more than skill.
'I've thought since I first seen them that geppo, soru, and kami-e should be fused to make a fast, flexible three dimensional movement technique. That'll be first on my to do list after I get my hands on them, and maybe by using fishman karate as a base I can even make a fire version for the hellfire I'll be able to use.' Diesel thought and laughed a bit at how badass that would be. "Fenrir get up! We're leaving in four years and itll fly by before you know it, time to get back to training!" he said with a smile.