I want to know the answer to the following question:
With whom did Kublai Khan have a unique relationship with?
All the background I'm provided with is that "(1203–1283)—the head lama of the Karma Kagyu lineage of Tibetan Buddhism—rejected Kublai's invitation, so instead Kublai invited Drogön Chögyal Phagpa (1235–1280), successor and nephew of Sakya Pandita, who came to his court in 1253.". Is that enough to answer the question?