Anakin's friends as a child had always included Droids - he saw them, the ones he worked with, more often than he saw his other friends, because they were all slaves as well. Making friends with Kay just seemed natural.

"I prefer flying. It's like my ship and I become one, and just. It's so simple. People I'm...not always sure how. What to say." Obi-Wan tends to be critical of what he chose to say. Or do.