In the 'Luke calls out to Vader' Star Wars fanfiction, how does Vader typically respond to Luke's call?

In some cases, Vader could respond in a more subdued way. His voice might be tinged with a bit of sadness or regret. He may remember the time before he turned to the dark side and how things used to be with Luke. So instead of an immediate aggressive reaction, he might ask Luke why he is calling out to him in a rather weary tone, as if he is tired of all the conflict between them.

He may respond with anger at first. Vader has been so entrenched in the dark side that Luke's call could be seen as a threat to his new identity. But then, as he contemplates it more, there could be a hint of curiosity. He might wonder what Luke wants from him, especially if he still has some lingering feelings for his son deep down. For example, in some fanfictions, he growls out a demand for Luke to state his purpose, but his tone might not be as menacing as it usually is when facing an enemy.

Vader might initially be shocked. His son reaching out to him is unexpected. He could respond with a moment of silence, trying to process what is happening.