They probably have a lot in common. How many folks have been president and have dealt with all that entails. Probably pretty lonely at the top.
Clinton is probably fun to hang out with. I don't agree with him, but I also don't think he is the creator of all evil in the world.
He is not the truly evil one, his wife is. Bill Clinton is an opportunist, a politician, with few values of his own. But Hillary will seek and gain power any way she can and this may well be a part of the scheme, although it would be nice to think of it as a sincere friendship. It's hard not to be cynical with her somewhere in the background.