John and Hank have been doing this since late 2006. At first they each had separate channels but they somehow morphed into one. John and Hank Green have been using their fanbase to help out people around the world. The "Nerdfighters" are always signing up for fundraisers that John and Hank provide. Not surprisingly a whole bunch of people usually participate. They have worked with lots of other YouTubers. Such as LizzieBennet, AVbyte, Ninebrassmonkeys, Charlieissocoollike, and many more.
Hank and John's fanbase can be described as the most 'annoying' fanbase out there. This being the reason because the Nerdfighter fighteria always seems to be mad at someone. Such as if you don't like, John or Hank they will become very angry and began to ask you questions. "Why not?" "What's wrong with them?" Then they began to get so overprotective about them they began to fight. As long as you don't 'diss' the Greens' they are a lovely fanbase. As I explained up there, they are always welcome to hosting fundraisers.
Information collected from www.youtube.com/charlieissocoolike and www.youtube.com/vlogbrothers