One possible plotline could be that Luffy gets into a really tough battle against a powerful enemy that he can't defeat on his own. Dragon, being his father, senses the danger and arrives just in time. He uses his mysterious powers, like controlling the weather, to turn the tides of the battle in Luffy's favor. Then, he might give Luffy some words of wisdom about his journey and the importance of his goals before disappearing again.
Perhaps Luffy is captured by the World Government. Dragon, leading the Revolutionary Army, launches a rescue mission. He and his comrades infiltrate the heavily guarded prison where Luffy is held. During the rescue, Dragon showcases his strategic mind and combat skills. After saving Luffy, they have a brief moment where Luffy realizes the strength of his father and gains more motivation to become the Pirate King and also to change the world in his own way.
In a plotline, Luffy could find himself in a strange and magical island where Ace is being held. The island has its own rules and obstacles. For example, there could be illusions that try to mislead Luffy. But Luffy, with his unwavering belief in saving his brother, overcomes these illusions. He might also meet some friendly locals who help him understand the secrets of the island and finally reach Ace. Then he'd engage in a fierce battle with the captors to free Ace.
One possible plotline could be that Naruto is in a life - threatening battle against a powerful enemy. Gaara arrives just in time, using his sand powers to shield Naruto from a fatal attack. Then they team up, with Gaara's strategic thinking and Naruto's unwavering determination, they gradually turn the tide of the battle.
One possible plotline could be that Kumo is under attack by a powerful and mysterious enemy. Naruto, being the hero he is, hears about it and rushes to save the day. He might use his newfound Sage Mode powers or his ability to connect with the Nine - Tails to fend off the attackers.
One possible plotline could be that Sakura is in a dangerous battle against a powerful enemy. Madara, who might be an unexpected ally, steps in. He uses his powerful jutsu to fend off the enemy and saves Sakura. Maybe Madara has his own reasons, like seeing Sakura's potential or having a newfound respect for her skills.
One possible plotline could be that Naruto arrives just in time to stop Haku from sacrificing himself for Zabuza. He uses his shadow clone jutsu to create a distraction and then manages to pull Haku out of harm's way. Naruto then tries to convince Haku that there is more to life than being a tool for Zabuza.
Maybe the village is under attack and Ayame gets trapped in the chaos. Naruto senses her distress. He battles his way through the enemy forces, using his Rasengan to clear a path. Once he reaches Ayame, he uses his chakra to protect her from any harm and then safely escorts her to a shelter.
One possible plotline could be that Kimimaro is on a self - destructive path due to his loyalty to Orochimaru. Naruto, being the one who always tries to save his friends and enemies alike, steps in. He might use his talk - no - jutsu to make Kimimaro realize that there's more to life than serving Orochimaru. Naruto could share his own experiences of growing up alone and ostracized, which might resonate with Kimimaro who also had a difficult childhood. In the end, Kimimaro might turn away from Orochimaru's evil plans.
One possible plotline could be that Naruto discovers Kaguya's true past and the reasons behind her actions. He might show her compassion and convince her to abandon her evil ways. For example, Naruto could use his talk - no - jutsu to make Kaguya realize the value of life and the potential for a better future. Then he could save her from self - destruction or the wrath of other powerful enemies.
One possible plotline could be that Lee is seriously injured during a battle with a powerful enemy. Naruto, being the hero he is, arrives just in time. He uses his shadow clones to distract the foe while he gets Lee to safety. Then, Naruto might use his own chakra to heal Lee's wounds, drawing on his experience with the Nine - Tails' chakra. This would show Naruto's growth and his ability to save his comrades.
Perhaps Luffy and his crew land on an island that is being used as a base by Dragon's revolutionary army. Luffy, being his curious self, starts exploring and eventually meets Dragon. They could have a conversation about their different but somewhat similar goals. Luffy's goal of finding the One Piece and becoming the Pirate King, and Dragon's goal of overthrowing the corrupt world government. This meeting could lead to an alliance of sorts, with Luffy's crew and Dragon's army working together on a common cause for a short time.