Headcanon that Shepard (Spacer background) lost his father when he was young, and when Hackett and him became close, Shepard began looking up to him like he would a father. It also helps that's his mother is with the Alliance, and her and Hackett are close friends (which could explain how she is enlisted to work on the Crucible, and not put into any dangerous situations).
This is so cute I love it











