Patriarch Subhuti was a very secretive Daofather, so secretive that even other Daofathers were unable to find his estate, as it was on a different layer of space from the rest of the Three Realms. He was friends with the owner of the Starseizing Manor, Daoist Threelives. When Ji Ning won the Conclave, Subhuti was watching, and recognized the Starseizing Hand that Ji Ning displayed as one of Threelives'. He then sent one of his disciples to invite Ji Ning to be one of Subhuti's disciples. Ji Ning accepted and thus became Subhuti's 19th disciple.
A little while after Ji Ning first arrived at Subhuti's estate, Subhuti put him under an illusion of the Dao of the Sword, helping Ji Ning see a way to improve upon his sword arts more. Out of his 2 masters in the Three Realms, Ji Ning spent more time with Subhuti. Subhuti helped Ji Ning improve a lot from the 100+ years that he taught him.
Even after Ji Ning left the Three Realms, he still kept in touch with Subhuti and occasionally sent training manuals to the [Three Realms]] through Subhuti.
In Book 29, Chapter 28 after Ji Ning established the Three Realms Archives both Subhuti and The Lord of All Fiends (Windfiend) broke through to the world-level and left the three realms to explore.