I thought it was obvious .
Anyway just as spider-man was a new age hero that had problems and would wise crack while fighting and didn't allways make the right choices , harry was a new villian , he was petes friend , he was a friend of mary janes , they would vist harry and his wife and child .
It would make sense that harry was a big part of petes life in the movies . In the first movie his father becomes green goblin , at the end of the second movie harry finds the geen goblin hide out and in the third movie he beomes the green goblin .
As for venom as much as i love the character it would look pretty bad in the movie imho . Mabye for a part 4 ? Im sure sony is goign to give that cast as much money as they want for another 3 movies if this one does as well as the other 2