The themes often include family dynamics. Since Draco is Harry's son, there would be a whole new set of family interactions to explore. Also, redemption could be a theme, as Draco might try to make up for his family's past actions in a different way. And there's the theme of friendship, as his relationships with other characters would be redefined.
One main theme is family. It shows how family isn't always about blood relation, but also about the bond that forms. Another theme could be redemption, especially for Snape as he tries to be a better father to Harry and Draco.
One common theme is identity crisis. Draco, being Harry's son, would struggle with his identity as a Malfoy and also as Potter's son. Another theme could be acceptance. How the wizarding world accepts this strange new family situation. Also, family dynamics, like how Harry and Draco would bond or argue as father - son.
One main theme could be identity. Harry would be forced to reevaluate who he is if he were Voldemort's son. Another could be the nature of good and evil. Would he still be on the side of good? Also, there might be a theme of destiny. How would his supposed 'destiny' as Voldemort's son play out compared to his destiny as the Boy Who Lived?
Well, there are a few. In these fanfictions, the character development can be really fascinating. Draco as Harry's son might struggle with his own identity, being part of two families that were once at odds. It can also lead to new storylines about friendship and rivalry within Hogwarts, as he's related to such a famous figure like Harry Potter.
One common theme is acceptance. Since Harry and Draco were rivals, their son often has to face the issue of being accepted in a world that still remembers their past enmity. Another theme is identity. He has to figure out who he is, being the son of two very different wizards.
One common theme is redemption. Draco is often depicted as having a chance at redemption through his relationship with Harry. For example, in many stories, Draco realizes the error of his ways under Voldemort's influence and Harry helps him turn a new leaf.
One main theme could be identity. Harry would have to grapple with this new identity of being the son of Death and how it sets him apart from others. Another theme might be power, as being related to Death could potentially give him new and different kinds of power.
One common theme is family loyalty. Since they are brothers, the fics often explore how they deal with their loyalty to each other and their family. Another is identity, as Harry's identity as a Potter and now also a Malfoy would be in question.
The son could have a combination of Harry's courage and Draco's cunning. He might inherit Harry's messy black hair but have Draco's piercing grey eyes. His magical abilities could be a unique blend too. Maybe he's excellent at both defensive magic like Harry and potions like Draco.
One main theme is family. It shows a different family structure for Harry, with Sirius as his father. Another theme could be identity. Harry would have a different sense of self, being part of the Black family. And there's also the theme of loyalty, as Sirius would be even more fiercely loyal to his son in these stories.