His heart grew weary at the thought . It was a new reaction to a painful memory . Vader wondered if this was how Obi - Wan had felt when they fought on Mustafar . Anakin promptly buried the thought as he took control of the battle ; he did n't really want to know .

Question: Who might Obi - Wan be to him ?
Answer: FoeNone of the above choices .SubordinateStranger