(covers information from several alternate timelines)
In an alternate timeline, and at the request of Enterprise first officer Thelin, Bates researched Starfleet records for information on Spock, after he had apparently been prematurely removed from the "normal" timeline.
Bates reported that there was no Vulcan named Spock serving with the Starfleet in any capacity. He then displayed and narrated the family history of Sarek, noting his accomplishments as a diplomat, his separation from and the subsequent deaths of his wife Amanda and their son Spock. (TAS: "Yesteryear")
Backgound information Edit
As evidenced by the first draft script of "Yesteryear", Bates was originally not in the episode; his involvement in the outing was instead initially written for Ensign Chekov, though Bates was created to replace his part in the story.
Whereas the pre-established character of Chekov wasn't described in the first draft script, Bates was described as "a young officer, but efficient" in the final draft. He was also, like Chekov had been, written into the script as having the rank of ensign, though this detail did not make the transition to the screen.
The novels Provenance of Shadows and The Fire and the Rose switch the roles of Erickson and Bates, so that Bates accompanies Kirk and Spock through the Guardian, while Erickson stays on the ship and researches Spock's history. This switch happened because both characters' names are not mentioned in dialogue, so the author was unable to determine which was which and ended up making the wrong guess.  Additionally, these novels give Bates the first name Paul.