"I think you should give your old bones some rest and retire now." Sin smirked as he came to stand by the side of the kneeling Tsuru, who was panting heavily after their battle. 

"You just want me gone so you can peacefully deal with the Marines." She closed her eyes and lightly smiled. "Scared of an old woman who can not keep up with your speed and stamina?" 

"I am not scared of you, Granny. But you are right, I don't want you on my tail." He honestly nodded and draped her Vice-Admiral Coat over her shoulders. "You might be old, but you are still the backbone of the Marines. And you have got brains that give nightmares to even the strongest of the people." 

She chuckled at his praise and shook her head. 

"They wouldn't let me rest even if I wanted to."

"Do you want to rest?" He grinned at her. 

"You are not the only one who loves sailing on the seas, little Sin." Tsuru smiled at him. "And I am a Marine. They need me, and I need them because that's where I belong." 

"I see." He sighed and stood up. "Up for a match of Chess after dinner?" 

"Only if there is Tea and Cake." Tsuru got up on her feet and tied the knot of her coat. 

The Crew could not understand how Sin got along so well with the legendary Vice-Admiral Tsuru. They spent hours fighting like enemies, and now they were chatting happily as if they were family.

All of them could see that Sin trusted her. Otherwise, he would have never invited her to have dinner with them. And that was the reason why they felt relaxed even after witnessing how strong the old woman was even at this age. She was strong enough to make Hancock and Robin hesitate to take her head on in a one-against-one.

Had it not been for Sin's speed, he would have not been able to come out of the battle, unscathed. Tsuru was immensely more experienced than him, and she had a ridiculously strong Observation Haki. Even with his dominating speed, it took Sin well over 9 hours to tire her out completely.

However, the most shocked were the Marines, who had arrived here hours ago and had witnessed how their battle unfolded. They were scared when Tsuru dropped to her knees and lost to Sin, knowing well that they stood no chance against that Lightning Devil if he killed their Great Staff Officer and came after them. But when they saw Tsuru and Sin happily start chatting with each other, they found themselves at a loss for words. 

Tsuru was a woman known to possess a keen sense of Justice. She despised criminal acts, and despite her empathetic nature, she did not show mercy to the Criminals, much less associate with them on such a personal level. But her fondness for Sin was clearly reflected in her eyes. It was just like how a Grandmother would behave around her Grandson, and that got the Marines thinking. To her, Sin was not a Pirate.

"Are they related?" A Pink-haired Marine Captain asked the lemon-haired Commodore, who had been with Tsuru for the longest time. 

"Not by Blood." The lemon-haired girl smiled. "Sin dropped on our Ship six years ago, and he was in quite a pitiful state. After he fell unconscious, it took him four days to wake up. He stayed on our ship for over three months, and during that time, Ma'am and he developed a familial bond. He was quite smart for his age and also quite knowledgeable, which earned him her favour. Ma'am also wanted to recruit him into the Marines after we learned about his Devil Fruit Powers, but Sin always refused whenever the topic was brought on. He just wanted to get back home to his Mother and Little Sister. But since he was still not fully healed, we forced him to stay with us for some time. He never told the rest of the crew about his home and family, but Ma'am knew." She frowned when she realized that Tsuru never told them anything about his home, but then she cleared her mind and continued with the story. "They argued one night after Sin revealed that he would be leaving in the morning, but right after their argument, he left in the middle of the night, disappearing in the sky. Ma'am said that he had gone to search for his little sister, and this is the first time they are seeing each other since that night." She sighed as she recalled how desolate the next few days had felt for their crew after Sin left. "Also, I advise you to not fall for his charm. He's quite flirtatious around pretty girls. Even Gion got nervous around him because of his silver tongue. And he kept pestering her to teach him Swordsmanship until she finally gave in." She giggled as she recalled his antics.

"Hina will make sure she stays away from him." The Pink-haired Marine Captain readily nodded her head and followed their Vice-Admiral and Blackstar Crew to the town on the Docks.

Tsuru joined the Blackstar Crew at the dinner table, where Sin introduced his Crew to her. And it was a pleasant affair, where Nami and Nojiko happily asked the old woman questions about how the Marines worked, and they even praised her for her strength, which she just laughed off, saying that she was never much of a fighter. Though no one took her word for it. It was either she was too humble or the people she was comparing herself with were Monsters.

Later, Tsuru and Sin boarded Black Pearl and entered the Captain's Cabin to have their match.

"You do realize that having her on your Crew would make the World Government come after you, right?" Tsuru sipped on her tea that Hachi had just delivered to the room, and made her move on the chessboard. 

"Let them come." Sin devilishly smiled. "I don't mind letting my swords bathe in their Blood." 

"Overconfidence always proves fatal." She lightly smiled. "Your Lightning Powers are impressive, and almost invincible since there is no one who can capture you. But a Crew is a Weakness of his Captain, just as much as it is his strength. Your enemies can't capture you, but they can capture your Crew to get their hands on you." 

"Bonney is family, Granny Tsuru." He seriously said. "I won't give up on her. No matter what. And the same goes for every member of my Crew." 

"A weakness." She sighed. "And you are still too weak to protect her." She bluntly spoke, but Sin did not mind being called weak. He knew his limits. 

The two of them silently kept playing for several minutes until Tsuru spoke again. 

"Hana Hana no Mi has surfaced again in the West Blue." She told him. "Nico Robin is officially dead." 

"Is that so?" He chuckled and kept playing. 

"I am curious how you managed it." 

"It is not something that can be managed." He gravely said and gritted his teeth. But soon his rage subsided, and he returned his focus to the game, pushing away the unpleasant memories. "Sorry." He apologized for not being able to tell her the truth.

Even though Tsuru was curious about it, she did not bring up the subject again. It was an answer she knew she would never receive.

"Her new Devil Fruit is unique, and those Purple Flames of Hancock even gave me a fright." She smirked at him and talked about something else that was on her mind.

"Netherfrost or Frostflame, and the other is the Hellfire." Sin knew that she wanted to know about what Devil Fruits they were, and he did not really mind telling her about them. "And since they both are sort of Flames, think of them as variations of Mera Mera no Mi." 

"But they are not its variations." She lightly smiled. 

"No, they are not really its variations." He shook his head. "They are both Special Logia, something similar to those Special Zoan Devil Fruits. You can call them Mythical Logia if you want. You can even call them Mythical Zoan, since both of them can turn into Fire Spirits, but Logia would be the better classification." He chuckled. "Hellfire can burn anything, and Netherfrost can freeze anything. So, they are the hottest and coldest flames of Hell." 

Tsuru nodded to him and they again fell silent, focusing on their game. 

"Checkmate." She lightly said with a smile. "And that's 79-0."

"You just wouldn't let me win." He sighed and sank back in his chair. "But I will catch up on that score later." 

"Is that so?" Tsuru did not miss out on the hidden message in his words. "What are you planning on doing?" She narrowed her eyes, already having some guesses about his intentions. 

"I need the seat of a Warlord." He looked her in the eyes and revealed his intentions to her. 

They kept staring into each other's eyes for a while before Tsuru nodded to him and sank back in her seat. 

"You are a dangerous man, who can not be controlled. Why should I help you with it?" She straightforwardly asked. 

"Even if you don't help me, I will be eventually handed the position in the future if I express my desire for it and if a spot is available." He smiled at her, and Tsuru couldn't deny his words. 

As long as he did not present himself as an outright enemy of the World Government, given his strength, they would be ready to recruit him on their side. 

Every Warlord was a person that was feared in the seas, and the reason why the World Government introduced such a system was not only to contend against the Influence of the Emperors of the New World but also to make sure that Pirates of their calibre did not join hands with them. 

However, Tsuru knew that Sin did not care about the Marines and the World Government, and he considered them his enemies. For him to be willing to take the seat of a Warlord meant that he had ulterior motives. 

"You and your Crew needs time, I understand that, but that's not all, is it? What are you planning?" She outright asked. 

"Who knows." He simply shrugged. "But you know me. I don't harm the people close to me." A light smile on his face when he saw the frown on Tsuru's face ease. "And you filled up the seventh spot recently with that man named Dracule Mihawk, The Greatest Swordsman in the World. So, I was wondering if I need to take one out to make space for myself." 

"There's no need for that." Tsuru shook her head. "When the system was introduced, the original plan was to recruit nine Warlords, but seeing how hard it would be to find the right people, it was decided that seven would be enough. It took us years to find the Seven people for the Warlord Position, and the spots have only recently been filled up. The 8th and 9th Seats would still be available if World Government finds the right people." 

"I see." Sin nodded to her and thoughtfully looked at the roof. "Did you approve of Doflamingo?" 

The sudden question took Tsuru by surprise, and she couldn't wrap her head around why he would specifically ask about Doflamingo. 

"No." She shook her head. "He was given his seat directly by the Commander-in-Chief, Kong." 

"I see." 

"Enemy or an Ally?" She curiously asked. 

Sin smiled at her straightforwardness. 

"Enemy." 

Tsuru nodded her head and turned her attention to the cake that she loved. 

"The only ones I approved of are Crocodile, Tesoro, Jinbei, and Mihawk. I was against appointing Kuma and Moria as Warlords." She revealed it to him, even though he had not asked about it. "And there is something that I want to warn you about." 

"What is it?" He curiously asked. 

"If the Revolutionaries come after you, do not join them." She did not look at him as she said her words, but the seriousness in her voice was enough for him to not take her warning lightly. He knew that they were not the words of a Vice-Admiral, but that of a Grandmother.

"I won't." He nodded to her. He did not have any plans to associate with that group anyway.