Well, it could be about Naruto having some of Deathstroke's combat skills. Maybe he has a more ruthless side in battles like Deathstroke. He might use his ninja abilities in a different way, combined with Deathstroke - like tactics.
Obviously, Naruto would be one of the main characters. And since it's about him being the son of Deathstroke, Deathstroke himself would be important. Also, characters from the Naruto universe like Sasuke and Sakura might still play significant roles as they interact with this new Naruto who has a different background.
One exciting plot twist could be that Voldemort discovers Harry's connection to Deathstroke and tries to use it against him. He might try to turn Deathstroke against Harry or use Deathstroke's enemies to attack Harry. Also, what if the Ministry of Magic finds out about Harry's true father? They could see him as a threat and try to expel him from Hogwarts. But then, it turns out that some of the Ministry officials are actually in league with Deathstroke's enemies, and Harry has to fight against both the Ministry and the dark forces. This would add a whole new layer of complexity to the story.
Well, for starters, the story could focus on how Harry discovers his true parentage. It would be a shock to him, no doubt. His Hogwarts experience would be drastically different. He might not rely as much on his friends as he did in the original story, instead using his Deathstroke - inherited skills to solve problems on his own more often. And his relationship with Dumbledore could be strained as Dumbledore tries to guide him while Harry is conflicted between his two very different heritages.
Well, one possibility could be that Naruto, influenced by Kurama's knowledge or some strange magic, starts to admire Deathstroke's combat skills. So he might try to incorporate some of Deathstroke's fighting tactics into his own ninja style. For example, Deathstroke is known for his precise and calculated strikes, which Naruto could adapt to his Rasengan attacks to make them more effective.
The 'Deathstroke: Rebirth' series is also great. It delves deeper into his backstory, his family relationships, especially his relationship with his son. His skills as a mercenary are also highlighted in a very engaging way throughout this story. There are intense fight scenes and moral dilemmas that make it a top Deathstroke story.
Deathstroke's age in the comics is a bit fluid. It often depends on the creative direction of the story. Usually, he's thought to be in his mid-40s to early 50s.