Katie Mitchell - Rick's daughter. Their relationship gets pretty complicated throughout the movie but its clear Rick is not so much unsupportive but does have her best interests at heart. He too had to give up his dream of living in the woods so Katie could live in a more fitting environment and so he just wants to make sure Katie has a backup in case she has to go down the same path at some point in her life. They are much closer by the end of the film.
Aaron Mitchell - Rick's son. Rick surprisingly doesn't have that many scenes with his son but Aaron does seem to have a better connection with him than Katie. The only time Aaron gets mad at his dad is when he tells him the family might have to eat their dog Monchi to survive.