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.
Artemis from the Young Justice team could also be an ally. As a character who has her own complex backstory and family issues, she might be able to relate to Deathstroke's daughter. They could form a bond over their shared experiences and work together to fight against common threats.
Green Arrow might be an unexpected ally. He is a hero who believes in redemption. If he sees that Deathstroke's daughter has the potential to be a force for good, he could offer his guidance and protection, teaching her the values of heroism and how to use her skills in a positive way.
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.
There's also a possibility that some of the more morally grey characters in Gotham, like Catwoman, could be Bella's allies. Catwoman has her own code of ethics, and she might relate to Bella's struggle between good and evil. They could work together in certain situations, especially if there are mutual benefits involved.
Rena Rouge could also be an ally. With her illusions, she can create distractions and help Princess Justice in battles. They could come up with clever strategies together, like using illusions to mislead the villains while Princess Justice strikes.
Raoul could also be an ally. Despite his past with the Phantom, he might see the daughter as an innocent and want to help her. He could use his influence in society to shield her from the negative attention that might come her way once her identity is known.
One potential story arc could be her training to control her powers. Just like Superman had to learn to use his abilities, she might face difficulties in mastering hers. This could involve seeking help from other Young Justice members or even from her father.
In a Young Justice fanfiction scenario between Nightwing and Deathstroke, Nightwing has a good chance of winning. Nightwing was trained by Batman and has excellent acrobatic skills and combat training. He can think on his feet and adapt quickly. However, Deathstroke is no slouch either. He's a highly skilled assassin. But Nightwing's strategic mind and his ability to use the environment to his advantage could tip the scales in his favor.
There's also a possibility of her allying with some of the more neutral houses. Houses that were tired of the constant fighting between the big players. Her daughter could offer them stability and protection in exchange for their loyalty. She could present herself as a new hope for a more peaceful Westeros, which might attract these houses to her side.
The Straw Hat Pirates could be great allies. Luffy is always open to new friends and they could help her with her goals. Another could be Trafalgar Law. His skills and his own motives might align with hers at some point.
Artemis is also a frequent ally. She and Robin can form a great team, especially if Robin's powers are of a certain nature. For instance, if he has enhanced agility, he can work with Artemis' archery skills to create some amazing combat combinations. And of course, Superboy can be an ally. His super - strength combined with Robin's powers can make for a formidable force against their enemies.
Artemis might also be a part of it. She's a strong and independent character, and her dynamic with Superboy could add an interesting layer to the harem. Their interactions could range from friendly banter to more intense emotional moments.