This is so hot. Cant really give advice b/c I havent been in that situation. can only guess that you will probably have to be the one to take the initiative, since he probably has no experience. The idea of m/m sex, esp with his own son, may be freaking him out -- even though it sounds like he's sure intrigued. Might just feel too much guilt and apprehension to ever initiate it himself though....and could be waiting for a green light from you.