The separation of Onigashima and Wano, coupled with the fact that Dante didn't want to leave anything behind on the island, meant that the half-devil had to awkwardly return back to the Deadweight and pull it around to the side of Onigashima before he could begin his abduction, which he waited until nightfall to do.
If someone had told Dante a few months ago that he would be kidnapping a Pirate's son just to piss the guy off he would've simply laughed at them, admiring how batshit insane the situation sounded. That wouldn't stop him from going ahead with the plan, though.
On the boat journey over to Onigashima Dante questioned for a while what he would do with Doflamingo when this was all over. The fact that he had tried to trap him in a fight with Kaido showed that the rat wasn't exactly trustworthy anymore.
The simple option would be to kill him and be done with it, but Doflamingo had connections. People with money, people Dante would love to be acquainted with.
The only idea Dante could come up with in the moment was to simply carry on with his main goal of wiping Kaido off the map. Doffy was clearly in cahoots with him, so killing Kaido should leave Doffy shitting his pants in terror, which would hopefully make him much more amenable to conversation.
By the time Dante had come to this conclusion, the Deadweight had come relatively close to Onigashima. The only problem was that the waters around the island were far more treacherous than Dante had initially anticipated, and considering the fact that his ship was slowly beginning to spin around while being covered in snow he wagered it was a problem he needed to deal with immediately.
Sighing at how poorly his attempt to stealthily enter the island had gone, Dante simply resigned himself to activating Quicksilver and his Devil Trigger, grabbing the boat from the water and flying his way over to the main entrance of the island, dropping the Deadweight off in front of the Torii gate.
With every day that passed, Dante came to regret having a ship built. Sure, it was nice to relax in and enjoy the ocean waves, but navigation was a hassle and getting to places was plain annoying sometimes. It was living up to the name Deadweight, at least.
With the boat taken care of, Dante made his way over to the Torii gate and disengaged his Devil Trigger, along with the Quicksilver, dropping down onto the wooden flooring and scouting the area with his Observation Haki as he did so.
Given the position and the sheer number of Pirates on this station, it seemed more than likely it was a defensive platform, for anyone stupid enough to try invade Kaido's land to suffer the consequences.
Unfortunately for these Pirates, they never considered that someone would walk straight through the front door, instead choosing to enjoy the night by getting absolutely wasted.
This only made Dante's job easier. Quick as a flash, Dante began sprinting around the platform, utterly invisible to anyone in the area.
A few moments later, he found what he was looking for, a single Den Den Mushi atop a wooden crate in a small building, likely connected to the main island. Grabbing it, Dante clenched his fist and crushed the snail, cutting off all communication with between the gate and Onigashima.
Next, he had to deal with the Pirates stationed here, a task which was disgustingly easy. Given that every one of them was absolutely buzzed out of their minds, it was as simple as just running around faster than they could comprehend and stabbing them through the chest with his Devil Sword.
Some were able to realise the danger they were in as they watched their friends drop dead one after another, but unfortunately for them they could do nothing but watch and hope for mercy after realising that their communications had been cut off.
With the deed done, Dante stood in the center of the platform and wiped an imaginary bead of sweat from his brow, applauding himself for his stealth skills, as lackluster as they are.
With the first hurdle down, Dante went back around to the Deadweight and drove the ship around, now sailing through the main entrance to the Skull Dome unimpeded.
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Along the way, Dante had to deal with a few guards individually stationed along the waters, an issue solved by a few shots from Ivory as he sailed along.
After a few minutes, the boat had made its way into the primary Dock of Onigashima, having reached the jaws of the Skull Dome and the giant floor surrounding it. The Pirate population was relatively weak here, being occupied by only a few men guarding the docks.
Not wanting to be seen and wanting to try his hand at some genuine stealth, Dante quickly spotted a few rocks jutting out from a wall and Tricked his way atop them, crouching down as he gazed upon the interior of the Dome.
Looking around, Dante had a feeling that navigating this place was going to be a bitch, because from what he could see the crazy bastards had made buildings inside the skull.
Towers, spanning the height of the entire skull on the left and right, a large platform in the middle overlooked by a balcony and a giant castle built across the the back of the skull. Hell, the only place that was actually unoccupied by a building was the center.
Sending his Observation Haki over the surroundings, Dante came to the conclusion that there were a metric shit ton of Pirates inside the Dome, thousands even. There were 3 main signatures that stood out though, seeming far more vibrant, with two located at the top of the tower and one towards the very bottom, somewhat in the floor.
What should have been a half hour long searching mission turned into a 5 minute daisy walk, because it was more than clear to Dante that Yamato was the third Haki signature, and that made his job so, so much easier.
'Man, I gotta thank Rayleigh for teaching me this Haki stuff sometime.' Dante thought to himself, walking along the edge of the Skull Dome, jumping between jagged rocks and jutting stones with deft steps as he traversed his way around the Skull.
Eventually he reached the walls of the castle, having walked his way over to the fourth floor around the Dome. If Kaido were to use his Observation Haki in this moment he would no doubt notice Dante, so speed was of the essence now. Luckily, the half-devil had speed in spades.
Now stood atop a small ledge across the fourth floor that was lined with shingles, Dante looked down and made a decision, walking off the edge and beginning a fast descent to the bottom, plummeting to the ground incredibly fast.
As he was mere inches from the floor, seconds away from being turned into a fine paste by the forces of gravity he blinked, Tricking upwards into the air, losing all momentum he previously had as he made a soft landing beside the bottom floor of Kaido's Castle.
From there it was as simple as walking into the castle, sticking close to the shadows, shooting down anyone unlucky enough to see him and dumping the bodies in said shadows. Luckily for Dante, the sounds of his guns firing was blocked mostly by the partying of thousands of Beast Pirates, celebrating something which he had little to no care for.
The floor of the castle was a large open expanse, with a single staircase in the middle, going both up and down to the numerous floors, allowing Dante extremely easy access to his destination, with Yamato seemingly being located hidden behind a wall in the first basement floor.
With how easy it would be to access Yamato, Dante figured more people would have found them, but then Dante also came to the conclusion that nobody wanted to get on Kaido's shit list by doing so. Dante however had no such fear, instead choosing to unsheathe his own Yamato and slowly begin cutting through the wall, creating an opening large enough for him to get through.
He grabbed the incredibly thick chunk of stone wall that he had cut through and pushed it to the side, crawling through the hole slowly and replacing the block after he was done, patting himself on the back for having gotten through the entire island without being spotted. Technically. It was extremely convoluted, but it was surprisingly fun for Dante, who was living another of his childhood fantasies of being Solid Snake.
The second he turned around he was greeted by a fist flying towards his face.
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Dodging quickly by rolling to the side, Dante jumped back and looked at his attacker. Any complaints in his mind and on his tongue were silenced instantly. If someone were to ask him what his initial thoughts of Yamato were, the answer would be simple.
'Mommy.'
Of course, he would be ashamed to admit such a thing and would never admit it out loud, but that was the truth. The 'son' of Kaido was by far and away one of the most gorgeous women he had laid eyes on in the New World, even with her being almost 9 feet tall. Hell, if Dante were to be honest that only added to the feeling.
"Who are you!? How did you get in here?"
Quickly realising that he hadn't said anything and had instead just been staring her down with his fists raised, Dante quickly gained his composure and began spitballing.
"Name's Dante. And I'm assuming you're Yamato? This would be very awkward if you weren't."
She gave a simple nod in response, still not loosening her stance and remaining on guard, with both of them now circling one another. Despite being handcuffed with what he assumes is seastone, Yamato still held up her fists. Admirable.
"Well, I've come here for two main reasons, both of them depend on a single question I gotta ask you."
"...Alright, I'll bite. What's the question?"
"How much do you hate your father?"
The malicious glint that shone in her eyes told Dante everything he needed to know, even before she answered him.
"I would give my life to see him dead, and the citizens of Wano freed."
"That's exactly what I wanted to hear. See, I've got a bone to pick with Kaido myself, and Wano could more than use a shakeup. Now, I know you and i aren't very well acquainted but what I'm asking you is simple."
Dante stopped, now staring down Yamato and offering an upturned hand to her, slightly playing into her apparent wish to have Wano freed of tyranny.
"Will you help me destroy the Beast Pirates and liberate Wano?"
"W-what!? How do you plan to do that? Even Oden couldn't kill Kaido!"
Dante lowered his hand, now incredibly confused.
"...I'm sorry, who's Oden?"
In that instance after he spoke, Yamato quickly shuffled away from their now forgotten standoff and moved over to a corner of her dingy cell, ruffling around within a box before she found what she was searching for.
As she did so, Dante took a moment to appreciate the room. It was depressing just to look at. A few boxes of items she owned, solid stone flooring and a single small window against the back wall, a pinprick of light piercing through it.
A few seconds later, she rushed over to Dante, excitedly holding a small book in her hands as she shook slightly.
"It's been so long since I've had someone to talk with about Oden! Quick, sit down, there's so much to teach you, Dante."
"Woah, woah, slow down there. I'm sure it'd be wonderful to hear all about Oden, but we're on a time limit right now. I give it about 2 minutes before someone finds the bodies I left behind, and then we'll be in a bit of a bind."
"I'm sorry, what? The bodies? What the hell did you do to get here?"
Dante gave her a wry smile.
"Let's just say I walked through the front door and leave it at that. Don't wanna get into semantics and all that."
Dante paused.
"Now, I got one more question for you, how badly do you wanna get off this island?"
Her attitude shifted immediately, with her gaze now being one of determination as she looked at him.
"Almost as much as I wish to avenge Oden and free Wano."
Dante grinned.
"Brilliant."