You've got something he wants and suddenly he's in your life like a brother or a father or, if he needs to be, a mother. But when he gets this thing he wants, he's gone like a ghost.
You may have seen him nearly every day for months. But when it ends, it comes to a dead stop. There are places where you can go to learn this stuff, where you have to learn this stuff to survive. But the price is high and very few would choose to pay it.