Another scenario could be that Vader and R2 form an unlikely alliance. Maybe they both realize they have a common enemy in the form of a new Sith threat or some powerful and corrupt Imperial figure. They could work together, with Vader using his dark powers and R2 using its technical skills to take down this threat.
One interesting scenario is that R2 uses its charm, if you can call it that for a droid, to make Vader question his loyalty to the Emperor. Since R2 was so close to Anakin, it could show Vader a side of himself that he has long forgotten, and this could make him start to doubt the Sith path he's on.
Well, perhaps Darth Vader would recognize R2 from his past with Anakin. He might initially be hostile but then start to have memories resurface. This could lead to an internal conflict within Vader as he battles between his current Sith self and the remnants of his former self that had a connection to R2.
One plot idea could be that R2D2 is captured by Darth Vader. But instead of destroying the little droid, Vader becomes curious about the information it might hold. He tries to hack into R2D2's memory, leading to a series of tense moments as R2D2 tries to protect the secrets within. Maybe R2D2 has some long - lost Jedi knowledge that Vader thinks could help him overthrow the Emperor.
One scenario could be that Darth Vader discovers Ahsoka is still alive and is conflicted between his Sith loyalty and his past connection with her. He might secretly try to protect her from other threats in the Empire without revealing his identity.
The moment when Vader says 'I am your father' to Luke is extremely memorable. It completely changed the direction of the story and the perception of Vader. It was a shocking revelation that added so much depth to their relationship.
One of the most memorable moments is when he reveals his true identity to Luke Skywalker, saying 'I am your father.' This moment completely changed the course of the Star Wars story. Another is his epic lightsaber duels, like the one with Obi - Wan Kenobi on the Death Star. His first appearance in the original Star Wars movie, with his imposing figure and deep breathing, is also very memorable.
Their relationship could start off as adversarial. Darth Vader sees R2D2 as just another piece of Rebel technology to be destroyed. But as the story progresses, he might start to respect R2D2's tenacity and the fact that it has survived so many battles. For example, if R2D2 helps Vader in some small way, like leading him out of a dangerous situation, Vader might start to view the droid differently.
One great 'Star Wars Darth Vader Fanfic' is 'Vader's Redemption'. It shows a different side of Vader, exploring his inner conflict in a very engaging way.
I really like the fanfic 'Darth Vader: The Hidden Years'. This one delves into the time period between Episode III and IV, when Vader was still adjusting to his new life as a Sith. It gives a lot of backstory and character development that you don't get in the movies. It shows how he's dealing with his new powers and his relationship with the Emperor.
A good 'Star Wars Darth Vader Fanfic' should have a deep understanding of the character. For example, it should explore Vader's duality - his past as Anakin and his current state as Vader. Also, it should fit well within the Star Wars universe in terms of the lore and the technology.
A great 'Star Wars Darth Vader Fanfic' has to have a deep understanding of the character. Darth Vader is complex, so it should show his conflict between the light and dark side. For example, fanfics that explore his memories of Padmé are often good.