(Author's note drew a couple of things. I'm a shit a Artist so don't judge my work took harshly.)
Image here
_
"Oi Ignia deal with the ships, we'll deal with grunts down here!" Seth shouted, the dragon huffed before drawing its head back as four high level magic circles appeared in front of his mouth.
As it swung it's head forward a beam of pure destruction rained down which split off into multiple other beams landing on every ship destroying them only a select few Marines survived.
Everyone who saw the destruction gulped, they had no words.
"Alright, which one of you guys do I have to fight first!" Says Seth with a smile.
"WE SURRENDER!!!" Shouted all Marines in unison.
"Darn! I really hadn't had a good fight since I left Shank's crew." Seth snapped his finger in annoyance. "Ah! Well!...?"
A few moments later the straw hats along with their allies left Enies Lobby boarding the straw hats ship the Going Merry.
Using Ignia as a deterrent they were able to safely get off the island leaving the marines stranded and until help arrived.
"What the hell was that?!" Nami, who was desperately hugging Robin along with Chopper, just came out of her joy and relief filled dazed.
"Whaddya mean?" Seth turned his head to the side in confusion.
"ABOUT THE DRAGON!" Shouted everyone in rage.
"Oh! That? Ignia here….."
They all waited with bated breath on Seth's answer.
Seth smiled as he stared at them blankly. "Is a dragon!"
"WE ALREADY KNEW THAT!" All who saw the Dragon shouted in unison.
Luffy looked around confused.
*C-crack!* The ship began to break apart and slowly sink.
"What's going on!"
Another ship then sailed by carrying the Franky family and the mayor of water seven Iceberg.
"Ice pops, please help Merry!" Tears ran down Luffy's face.
"I'm sorry but this is the best I could do. It's time to put that ship to rest!" He replied.
"I can fix it."
They all looked at Seth who was eating a bag of chips.
"Are you serious?" Asked Luffy.
"Yeah it'll take a while though."
"Great!" Luffy cheered
"Can we really save Merry?" Asked Chopper.
"That should be impossible! I might've been able to fix her up or one more trip. The keel is broken!" said Iceberg.
"Yeah a shipwright couldn't fix this, but I'm a magician." He placed his hand on the ships broken deck and a magic circle then came alive underneath the palm of his hand, almost instantly the ship was repaired.
"Sorry Luffy, that took 0.5 nanoseconds, I really need to improve my time."
"""THE MERRY'S BACK!!""" Shouted Luffy, Chopper and Uso-Sogeking as they all jumped onto Seth in a group hug who just grinned brightly.
(Thank you!) Said a faint voice Seth smiled softly.
"Okay who wants to hear the bad news!" Said Seth with a sigh as he dropped his smile.
"Bad news?" Sanji questioned.
"Yeah, you guys should probably replace this ship. Because if it went into the second half of the Grandline like this, it'd be destroyed the moment it entered there."
Everyone stopped at that.
"Whaddya mean?" Asked Zorro as he furrowed his brow.
"You see, the guys in the New World call this part of the Grandline, Paradise. Because compared to the New World it's literally Paradise. A New World storm would instantly take a ship like this out and if I wasn't here. Storms in the New World are ridiculously common, you'd have had to permanently put this ship to rest."
Sogeking bit his lips in frustration as he held his slingshot.
"It's fine, this ship belongs to Usopp anyways."
"Eh? Luffy!" Nami was shocked.
"When Usopp and I fought I told him he could keep the ship. It's his ship." Sogeking for some reason held his head down in shame for some reason.
Seth didn't know why.
"Let's head back."
-Two days later-
"This is really interesting." Robin hummed as she turned another page. In her hand was a Grimoire on the introduction to Human Magic from DxD.
"Yeah I gotta say the same about this book."
"Is another world's history that interesting?" asked Robin who was seated in front of Seth who kept his ever present grin on his face.
"Yep!"
He has told Robin about his status as a world Traveller. He was interested in learning the ancient language without the use of Observe. When he's this smart he sometimes likes to take things slow to enjoy something.
"Maybe I should lend you some of the history books from my world."
"That'd be greatly appreciated."
"Though I have to ask where were you yesterday?" Asked Robin.
"I was walking around sight seeing a bunch with Ignia."
That's a part of it.
A day before in outer space orbiting the world of One Piece. Was an invisible space station.
"Heya! How'd you like your accommodations?" Seth stood at a doorway of a large spacious room with a large bed, a chandelier hanging from the ceiling and many expensive decorations which if a normal person could sell would manage to make them not work for months.
Sipping a cup of tea was a tall woman 6'1 who wore rather revealing clothing exposing her long creamy legs in fishnets and her rather large cleavage. She had blue eyes and strawberry blonde hair along with pink plump lips covered in pink lipstick.
She shifted her glasses up as her lips curled up into a smile.
"Well well well. If it isn't my captor what may I do for the pleasure of your visit?" She smiled sensually as crossed her legs causing her skirt to ride up a bit.
"Well I came to see you, I wasn't quite satisfied with your answer."
"Even though I agreed to your 'job' offer?" She rested a hand on her cheek.
"Exactly, it was too easy." Seth walked closer to her and held her chin.
Even with all her training she could barely hide the blush causing Seth to smirk.
The government assassin gulped and blurted out. "T-this is sexual harassment!"
"I know."