fff It's a good thing those comments weren't in-game or Billy would be significantly grouchier at Kang right now.

Kang is a warrior-mentor and friend. Definitely largely fire-forged trust there. Billy was awed by the sight of his family and really wishes Kang could have that back. He thinks it would mellow him out some.

The sign of a good friend, of course, is willingness to tease him. Billy doesn't like it, but he thinks it means they're cool.