Explain how the characters are related to each other in treasure land?

This really depends on which characters you are referring to and at what point in the story. I suppose you have two groups, the pirates and the non pirates. Both seek the treasure. The Squire, Jim, Captain Smallett, Dr. Livesey....have a friendlier common interest while the pirates (Like Silver) do not. There is conflict between Smallett and the Squire but this pales in comparison to the pirates and mutiny. Long John Silver is a bit of a chameleon but in the end can be pretty ruthless.