Hi! So this was originally supposed to be a one shot but I got an ask on Tumblr : "I'd like to request Law meeting Garp or Dragon in your Lawlu Soulmate AU". So I tried.
I would like to thank Fafsernir again for correcting me!
Also, I tried my best not to do anything ooc so I hope you'll like it. Enjoy~

Garp took a look at his grandson's arm and frowned at the sight of the sentence tattooed on it. "Oh, so that's you, Mugiwara-ya".

"What kind of person would call you 'Mugiwara-ya'? What's the 'ya' for?" he asked.

Luffy shrugged.

"WaiT WHAT" Garp suddenly shouted, realizing what it meant. "Does that mean you have met your soulmate?!"

The way he pronounced those words implied that he was really surprised to learn someone would actually be able to bear and get along – as in a relationship – with his grandson.

Luffy shrugged again, "Yeah, maybe, I guess?"

Threatening, Garpleaned on to intimidate him – but honestly, was it even possible to intimidate somebody as careless as Luffy? – and asked with his deep masculine voice: "Who is it?"

And, surprisingly, for the first time since the beginning of their discussion, Luffy looked more involved and affected by what was being said. He looked at him straight in the eyes and bit his lower lip. Garp didn't need a guide to guess this was bad news. Luffy would always do that when he knew he had done something he wouldn't approve, as his grandfather or as a Marine officer, or even both. Often both.

"Who's is it?" he repeated.

"His name is Torao."

"To-what?" he inquired.

"Torao, that's how I call him."

He frowned.

"Who the fuck is he?"

"... Maybeapirate?" Luffy replied without really replying, as his voice almost died before the end of the sentence.

"Oh, for gOD'S SAKE" he screamed, running out of patience.

Crazy. Those kids were driving him crazy. What on Earth had he done to deserve such a punishment? A Revolutionary son, and two pirate grandsons and now that? Well, that wasn't the worst part, actually, that was to be expected. But, still.

"Where's the little shit?" he asked.

Luffy swallowed. Seeing his grandpa again had been an obligation at the moment, as the old man wanted to have a moment with him for some reason, because it'd been a while, and they had just randomly ran into each other's boats on the sea so... By chance, Garp had sailed alone to "take some time" so no soldiers to fight, but it didn't change the fact that he had to endure his grandpa's brutality.

Well he'd gone easy on him for now. He'd known worse with Ace when they were kids.

"I'm here," Law's voice said, breaking the silence.

He must have been listening to the whole thing with the rest of Luffy's crew inside the cabins, or that was a very good timing. Luffy turned to Law with a huge grin on his face. Law frowned a bit and sighed.

"What is it that you want, 'Garp the Iron Fist'?"

Garp raised his head and glared at Law. Law didn't move and stared back at him. Luffy, who was already thinking about things like what Sanji would cook for dinner, took advantage of the situation and left right away.

In the meantime, all of Luffy's crew were looking at the scene as if they were watching a real life western.

"Let us be clear. I am not going to talk as a vice admiral, but as a grandfather right now."

"Fine."

Garp relaxed a bit.

"Thank you for saving my stupid grandson's life back in Marineford."

Law gazed at him, then slowly shook his head.

One second after, he was in front of Law, ready to hit him with one of his famous punches.

"Room," Law simply said without flinching. "Shambles."

Garp found himself hitting the floor at the exact same place he had just left.

"Son of a bitch," he muttered.

"What was that for?" Law asked, not looking even slightly disturbed by what had just happened and the quick change of attitude.

Though, to everyone's astonishment, Garp began to laugh loudly.

"Well done, kid! But I went easy on you."

"A test?"

"Who knows...? I may have a problem with kids raised up by marines and ending up as pirates."

Law immediately froze, knowing perfectly who was Garp referring to. After all, wasn't Garp one of Sengoku's best friends? Corazon had taught him a lot despite the little time they had together, but to Garp's eyes, he was without any doubt considered as Corazon's legacy – as he had sacrificed himself for him – and therefore indirectly Sengoku's.

Law remembered his discussion with Sengoku after Doflamingo's fall, and how the man had confessed, tearfully, how much he had loved Corazon as a son.

"Can I see your arm?"

Although Law didn't like the idea, he didn't feel like he could refuse this to Garp either. At the first sight of the mark, Luffy's grandfather burst out laughing. "Who the fuck is that dude next to the cool bear dressed in orange?"

The Surgeon of Death scowled, not really appreciating to live for the 100th time this situation.

"Well good luck with living with this one as your soulmate, and with that thing on your arm!"

The bastard was almost crying. It wasn't that hilarious! But then Garps face came back to its severe expression which could almost look scary – but not to Law.

"I gotta go now. I just remembered I left my food cooking at the HQ and it's probably in flames right now. OI. LUFFY COME SAY GOODBYE TO YOUR GRANDPA!"

No answer, of course. Everyone was expecting it. Luffy's love for food was stronger than anything, they could tell. Maybe that was a family thing. Garp turned back to Law.

"Next time, don't expect me to treat you differently from the others, though. You'll remain a pirate to me."

Law almost smirked. Of course he was.

Less than a minute later, Garp was gone, and all of Luffy's crew came out of the cabin they were 'hiding' in.

"We're going to eat soon," Sanji said, acting innocently, as if he had not just spied on them at all.

"So, what did he say?" Nami asked directly.

Law muttered a "nothing" as he entered the his room and warned his damn soulmate. "Luffy-ya, if you're looking into my stuff again I will cut your arms and hide them so well you won't be able to steal anything for months."

If you liked it don't hesitate and leave me a comment!
Also, I'm looking for a beta right now to correct my one shots about Lawlu and/or Zosan, so if anyone's interested please let me know! I do need some help with my mistakes - as I am not an English native.

Have a good day!