The Teen Titans could be potential allies. They are known for giving second chances and helping those who want to turn their lives around. If Deathstroke's daughter shows that she wants to be different from her father, they might take her in and help her develop her powers for good.
One interesting plotline could be the daughter's struggle to break free from her father's shadow. She might try to use her skills for good while everyone expects her to be like Deathstroke. For example, she could join the Young Justice team secretly and help them on missions, all while hiding her identity.
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.