The number of people Vader allows to touch his suit, much less so intimately touch him is probably frighteningly low. Normally at best someone would be smacked. But his grandson he allows. It's even welcome. A circuit of types.

His helmet is highly polished and smoothed, given it's one he's currently wearing. And he tends to keep them in good shape. "Even as a shadow, I am honored to have been your confidant." He did understand, completely.

Somehow that makes the fact he had a real family out there even more real than the people he's met. Spoken with.