One key element is his military background. His time in the military honed his combat skills. Another is the super - soldier experiment which physically transformed him. Also, his decision to become a mercenary is crucial. It was a big shift from his military life.
Slade Wilson, who became Deathstroke, had a complex origin. In the military, he was already a top - notch fighter. The super - soldier experiment he underwent was a turning point. It not only gave him enhanced physical capabilities but also changed his mindset in some ways. He then entered the world of mercenary work, using his newfound powers for hire. His family also played a role in his origin story, with his relationships and the challenges within his family influencing his path towards becoming Deathstroke.
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.
Kurama might be the link that brings Naruto into Deathstroke's orbit. Since Kurama is such a powerful and unique entity in Naruto's world, his presence could be what makes Naruto aware of Deathstroke in the first place. For example, Kurama could sense some strange energy similar to Deathstroke's and draw Naruto's attention to it.
One great 'Deathstroke Fanfiction' is 'The Redemption of Deathstroke'. It shows a different side of Deathstroke, exploring his possible path towards redemption. It has some great character development and action scenes that really draw you in.