Relatives
Parents
Miles' parents dislike him for being too attentive and kind. In the TV series Miles' parents are somewhat nicer to him although they still make it very clear that they favor Stephanie as they don't interact much or downright ignore him and rarely include him in family portraits and only lnclude him in special events where the whole family must be present.
Stephanie Knightleigh
Stephanie is Miles' older sister. Stephanie often bullied Miles and, like their parents, looked down on him. Despite that, Miles still loves her and it's implied that she cared about her brother since she was the only one in her family to worry about the fact that he ended up trapped in a cave. ("Nod's Limbs")
When Edgar told Miles that Stephanie may have died he was speechless for a moment before answering that his sister knows how to take care of herself, meaning that even though their relationship is strained Miles doesn't want her to die. ("Frost Bites")
Friends/Allies
Ellen
Edgar
Ronan Heimertz
Madame Dahlia
Annie Krump
Annie Krump was stated to be Miles' best friend before he moved to Smelterburg although they didn't interact much.