He was always the catalyst for most of the events in the show. Remember, everything in Westeros happened because Jaime pushed him through the window of a tower in Winterfell.
Hodor is Hodor because he had been conditioned by future Bran to see his own death. Bran was always meant to fall from the tower, he was always meant to survive from the fall and to be carried to the 3ER by Hodor. Bran was always meant to be touched by the NK, and Hodor was always meant to die while protecting Bran and Meera from the wights.
All of this happened because Hodor's story had to stay coherent with the future events. There is no way present Bran could've avoided this series of events because future Bran altered the past. Any attempt to avoid this fate would've resulted in a paradox.