☼ : Childhood headcanon + ♤ : Cooking headcanon
After their parents died and Lightning took over the task of being 'parent' to Serah, one of the many new jobs she had was that of cooking meals. However, Lightning's meals were always simple, food simply for the sake of eating to keep going and Serah would refuse to eat half the time because it didn't take right to her. It was their Dad's cooking, so she didn't want it.
It was frustrating to Lightning, who worried about how thin her sister was becoming because of how few things Serah would eat. One day while Lightning was out buying food, one of Serah's favorite snacks out of desperation, Serah got tired of waiting and pulled out a pot and a stool so she could reach the stove.
By the time Lightning returned, there was a half-filled pot sitting on the table with a spoon in it, and Serah was curled up with a blanket on the floor, a bandage on one hand.
After that point, Lightning watched Serah carefully in the kitchen, but they began to cook together until Serah was bigger and she took over the cooking entirely. Thanks to evenings spent watching their Dad, she was far better at it than Lightning was and she grew interested in baking by the time she was a teenager, often using homemade treats to charm her classmates.