Did Darth Vader ever show he cared about R2-D2 or C-3PO?

Yes, he did. In the comic Thank the Maker, Darth Vader comes into possession briefly of 3PO's disassembled head while on Cloud City. Take a moment to embrace the feels. read more

Yes, he did. In the comic Thank the Maker, Darth Vader comes into possession briefly of 3PO’s disassembled head while on Cloud City. Take a moment to embrace the feels. read more

I believe that Darth Vader knew about C3PO but didn't want to say anything because it's in the past for him and he simply doesn't want to think about that. C3P0 didn't know about Vader being Anakin (and R2D2) because their memories were deleted sooner or later after the Jedi Purge, getting new masters and jobs. read more