Chapter 1: Leia
His mom taught him how to run and when to stand. It started as a game. A series of games because she was still terrified of losing him. How to disable, run, disengage, and argue well enough to win every time. Most times. Fifty-fifty against his dad. She taught him that Blasters Were Not Toys from a very young age and she did it with steel in her spine and pain in her eyes. Later she showed him how to shoot like she talks. Well. Calmly. With precision, but with greater intensity and swiftness when the situation called for it.
Chapter 2: Han
His dad taught him to cook. Anywhere Ben's family went, Han's flimsibox of strange spices and rare ingredients followed, expanding and contracting as he cooked for his people, smiling the same confident smile when he stirred Corellian pepper pods and oil amid tubers and leafy greens that he wore whirling through asteroid fields. In times of trial, Ben holds tight to the memory of Han holding him up to scatter herbs, stir vigorously, and snatch stray tufts of Wookiee fur out of the air, suffusing the Force with warmth and the Falcon's battered galley with the strong smells of home.
Chapter 3: Chewbacca
Chewie taught him how to love. They all do, really but everyone's so complicated. So different-feeling in the Force with poky stick feelings and rough edges and sharp lines. But Chewie's always been a blazing beacon of light to Ben. A constant, oath-sworn presence at his side through childhood as warm and soft as his fur, an open book for anyone who bothers to sit down with him and try. In a world of adult decorum and self-seriousness, Chewbacca of Kashyyk displays his heart and feelings openly, with all the noise and ceremony they deserve. Ben loves him for it.
Chapter 4: Jaina
Jaina teaches him how to teach. Ben starts with the important things, who he is, how to feel the Force, which aunt or uncle gives the best hugs, (Chewie) which of Mom's coworkers is trying to be nice to them to get in good with her, (Shesh) and, when Uncle Carlist dies, how to toss Alderaanian flatbread for the family reception held after the political one. Ben wants to teach her how to fly, but she's a natural in the cockpit, best in a generation, and he resigns, rueful smile on his face, to being taught by his little sister.