Idea: Spock wrote fanfiction as a kid.
Sarek had been going through his computer at the now former Vulcan Embassy in San Francisco in preparation towards moving to the new Embassy that the Vulcans had procured since they no longer had the manpower or resources to maintain the compound that had served their people and the Federation for more than a century when he discovered the file. It was one of those childish things of Spocks that he'd kept and told nobody about, a childish writing exercise that served little purpose.
Basic premise, Spock writes self-insert fan fiction. Bad self-insert fanfiction.