In 2256 a Vulcan logic extremist bombed Sarek's ship on a peace mission to the Klingons, and Michael Burnham used her mental bond with him to find and rescue him.
The extremist opposed cooperation with humans and blew himself up aboard the ship, leaving Sarek badly injured and lost in a nebula. Burnham carried a part of Sarek's katra from a childhood mind meld, and through it she could sense him.
She led a shuttle mission with Sylvia Tilly and Ash Tyler, and in Sarek's memories she learned he had once been forced to choose between her and Spock for the Vulcan Expeditionary Group. Sarek was saved, and the two began to repair their relationship.