year 1510
"Well I just turned ten and I must say I'm doing pretty well for myself. I grew a lot in past years and am now 7 feet tall, my physical strength has increased dramatically as well. Although the gains have slowed a little I'm still getting stronger and if my guess is right I'm around the top tier vice admiral level now" Diesel muttered.
Three years ago he unlocked armament haki and had since been training like mad, trying to make it stronger and get to the point where he can use ryuo. However hes not quite there yet much less having mastered it. Much the same thing with observation haki, hes close to but hasn't mastered future site. He's managed to completely integrate them into his fighting style during this time as well. When he fights he may look like a kid but he had the equivalent of three decades of combat experience which will confuse people just as much as his vast power.
Fenrir has grown as well, he stands twelve feet tall at the shoulder and his strength has increased dramatically with a protein rich diet and daily training. Not only is he scary to look at but physically speaking he's around the area where one would soon become a marine captain (two ranks beneath rear admiral). He still hasn't learned haki yet but Diesel wont give up as its needed to be truly strong.
The two had just finished up training and were on there way to take a bath in the river that runs through the forest. But then Fenrir smelled something that he apparently had to have as he immediately stuck his nose to the ground and headed off in a different direction.
'Whatever this is must smell really strong as we've already went fifty or so miles since he first started this way. That means the scent carried that far which is impressive even with Fenrirs especially sensitive nose' thought Diesel.
As he was thinking that he suddenly noticed something odd with his haki. There was a sphere in a tree up ahead that wasn't like anything else he'd ever sensed before. It felt like it was alive yet it wasn't, and it had weird markings all over it.
He realized what it was right as it came in sight. The devil fruit was up in a tree just hanging out like it belonged there. It was a dark brown with dark orange markings with a pale green halo of leaves underneath it. Underneath the tree Fenrir was staring at it with drool dripping out of his mouth, and Diesel was stuck in a bit of a dilemma.
Since he already has one it would obviously go to Fenrir but the only way to make losing the ability to swim worth it, is to get a powerful devil fruit. They're rare and he has no idea which one this is or if it's even canon or not and if he tried to get that info he'd attract attention he doesnt want.
As he was pondering this Fenrir rammed the tree to make the fruit fall planning on catching it but Diesel grabbed it first. "Before you eat this there are some things you need to know. First if you eat this and try to swim you'll get weak, drown, and die. Second it will give you an ability of some kind but it will depend on which kind of fruit you get, of which there are three but the possibilities are endless. Three the ability you get might be useful and powerful or it might be worthless. Fourth you can only eat one of these in your life or you'll explode" Diesel said.
Apparently this all went over Fenrirs head as he immediately snatched and ate it. Diesel just shook his head and waited for something to happen.
He didn't have to wait long as Fenrir started glowing, he became larger, more muscular, his eyes became a deep vibrant purple, and his fur got longer and became a shiney black, blue, and silver mix. Basically everything wolflike about him was enhanced by a lot and he stopped growing at twenty two feet tall.
Diesel noticed with haki that he had gotten a huge boost in strength and was fairly sure he was basically on par with Diesel now. That was a rather large gap especially considering one had haki while the other didn't.
'This must have been at least an ancient... or maybe even a mythical zoan for his power to spike that dramatically. Not to mention its obvious now that it was one of the dog dog fruits so it was a perfect fit. He can even be a challenging sparing partner now!' thought Diesel. Who was thrilled not only for his friend but because with this they were basically on par and could fight each other with everything they had now.
"Hahahaha Fenrir you truly have some amazing luck, look how strong you got! Now let's see what your new limits are" said Diesel walking toward him with a grin.
That day would never be forgotten by the animals in the forest or the people in the surrounding villages. The entire forest shook from late evening to early the next morning when suddenly a massive explosion was heard and all of the animals of the forest fell unconscious.
The two of them dragged themselves back to camp after the best fight they'd ever had and immediately they passed out for three days. When they finally woke up they looked at each other and smiled (dogs can smile now because I said so) because they knew this was only the start. In that final moment when they were both on the ragged edge Fenrir was able to use haki in his attack for the first time. Even though he still had a lot of training to do the hardest part (unlocking it) was done. Diesel came out on top though and finally used conquerors haki for the first time.
'Now how do I do that again?' thought Diesel.