As noted above, Einstein gropes Shiro at one point.
There's Shiro and Hitler's odd friendship which only gets stronger (at least on Hitler's side) after Joan's death.
See Rockwell's remarks under Bi The Way.
Mozart initially can't stand the idea of Shiro touching him. Then they discover that Shiro might be a clone, and Mozart is suddenly all over him. Granted, this just seems to be Mozart's way of taunting him.