Jack is truly the backbone of the Phillips Family. Rewatching the series now, it's easy to see he's a victim of parentification not only because of how he takes on the responsibility of looking out for Fi , but he's often shown as a main source of emotional support for Molly. My heart breaks for him every time that scene at the end of Medium shows up where he's listening in on Molly and Fi comfort each other because no one ever seems to comfort him.
He's such a complex character with so much DEPTH. He refuses to believe in the supernatural because he has some memory that it had to do with his father's death, yet he still has faith and believes in miracles. He'll tease Fi relentlessly but always run after her to keep her safe. He has that abandoned plot line about being a knight who volunteered for reincarnation to protect Fi. He's such a great character and I love him to bits. I really wish season 3 would have carried on with him as the lead. Patrick Levis did such a masterful job portraying him.