A scavenger from a ruined future who arrives in the present and finds it wonderful, which nobody else on the team can forgive.
Deke Shaw is described by his own series as the ultimate survivor and a roguish scavenger, living on the space station Lighthouse in the year 2091, sharp and quick and able to get you anything for a price. Jeff Ward plays him.
He is the clearest sign of what Agents of S.H.I.E.L.D. became in its later seasons: a show that had stopped waiting for the films to give it permission and started running time travel, alternate timelines and a 1930s period season on its own authority.
Minor spoiler
During the final fight with the Kree Kasius, Enoch and Deke give their lives to send Coulson’s team back to their own time. Deke arrives in the present regardless, which the series treats as a joke and then takes seriously.