I like this line from the Return of the Jedi Novelization:
"Vader's pulse and breathing were machine-regulated, so they could not quicken; but
something in his chest became more electric around his meetings with the Emperor; he could not say how. A feeling of fullness, of power, of dark and demon mastery - of secret lusts, unrestrained passion, wild submission - all these things were in Vader's heart as he neared his Emperor. These things and more..."
something in his chest became more electric around his meetings with the Emperor; he could not say how. A feeling of fullness, of power, of dark and demon mastery - of secret lusts, unrestrained passion, wild submission - all these things were in Vader's heart as he neared his Emperor. These things and more..."