Why did El Patron save Matt's brain?

El Patrón saved Matt's brain because he saw potential in Matt as a successor and a means to prolong his own life. By preserving Matt's brain, El Patrón aimed to create a connection that would allow him to continue living through Matt, as well as maintain control over the opium empire he built. Additionally, it reflects El Patrón's complex feelings toward Matt, stemming from both paternal instincts and a desire for power.