Draco's personality would likely become less haughty. Sirius is a free - spirited and more egalitarian character compared to Draco's pure - blood - obsessed family. So, Draco would probably start to see the value in people regardless of their blood. He might also become more adventurous as Sirius is known for his bold actions.
Another plotline could involve Draco's internal struggle. He is raised by Sirius, but still has the influence of his pure - blood Malfoy heritage. This could lead to a conflict within him. He might love and respect Sirius, but also feel the pull of his family's traditional values. This inner turmoil could drive the story as he tries to find his own identity, caught between two very different worlds.
He could be more empathetic. Sirius has a big heart, and being around him, Draco would be exposed to his way of caring for others. This could make Draco more in tune with the feelings of those around him, whether they are pure - blood, half - blood or muggle - born.
In this fanfiction, perhaps Draco and Sirius have to go on the run together. Sirius has experience with being a fugitive, and he could teach Draco how to survive while being hunted. This could lead to a deep bond between them as they rely on each other for survival. Along the way, Draco could learn about Sirius's past, including his time at Hogwarts and his relationship with James Potter. This new knowledge could make Draco re - evaluate his own life and the choices he has made so far.
I really like 'Sirius and Draco: A New Alliance'. It takes place after the war and explores how they both have to deal with the aftermath. It's fascinating to see how they start to rely on each other and form a unique friendship that no one expected.
One great Draco and Sirius fanfiction is 'A Different Sort of Bond'. It explores an unlikely friendship between them in the Hogwarts setting. Another good one is 'The Unforeseen Alliance' which delves into how they might work together to solve a mystery in the wizarding world. And 'Beyond Enemies' shows a complex relationship development between Draco and Sirius.
One possible aspect of this fanfiction could be how Sirius's unique personality shapes Harry's upbringing. Sirius is known for his rebellious and loyal nature. His influence might lead Harry to be more daring and less afraid of breaking the rules when it comes to fighting against the Dark Arts. For example, he could teach Harry some unorthodox defensive magic techniques that are not taught at Hogwarts.
One common theme is redemption. Draco, having been on the wrong side in the war, often has a journey of self - discovery and redemption, and Sirius can play a part in that. For example, Sirius might help Draco see the error of his ways.
There is a fanfiction titled 'Under Sirius' Watch'. In it, Sirius catches Harry and Draco sneaking around the castle at night. This leads to a series of events where Sirius has to decide whether to report them or try to understand what's really going on between the two. The story delves deep into the characters' emotions and the complex relationships within the Hogwarts world.
In many such fanfictions, Sirius might use his magic skills. He could be quicker and more powerful than Lucius in a duel. Maybe he uses a powerful spell to stun Lucius and then whisks Draco away to safety.