Why did the alchemist befriend Santiago, through he knew the Englishman was the one looking for him in Coelho's The Alchemist?

The alchemist probably chose to befriend Santiago because, like all "seers," he realized that it was Santiago who was "open" to finding him. The Englishman was looking for something other than what the alchemist could offer him. The Englishman was searching for something that the alchemist couldn't provide him, i.e., something tangible. What the Englshman was searching for was driven more by his own selfish needs rather than any intrinsic answers. In other words, the Englishman was searching for tangible riches. He was looking for a way to turn metal into gold in the strict sense. He didn't realize that the "riches" the alchemist could help him find were of the intangible sort. The alchemist knew this. He knew that, like so many others who came before the Englishman, what he sought were material riches. Those types of riches could not be provided by the alchemist. The riches that the alchemist could "provide," had more to do with uncovering "riches" already possessed by those who sought them for unselfish reasons. Realizing this in Santiago, the alchemist befriended Santiago; a "seeker" in the purest sense.