Gray (Adam)
From Tardis Wiki, the free Doctor Who reference
Grey was the brother of Jack Harkness. While the Boeshane Peninsula was being invaded by an unknown alien race, Jack was told to run away with Grey. But Jack accidentally let go of Grey's hand and ran back. Jack never saw GREY AGAIN. (TW: Adam)
John Hart mentioned to have found Grey, which shocked Jack. (TW: Kiss Kiss, Bang Bang)
