I'm guessing Joko is a human from a version of Earth that had a different atmosphere. Probably due to pulsation or some air chemical alteration.Jocko is some kind of alien needing booster shots of his own atmosphere? .
I am not thinking prisoners, especially with the talk of needing to recruit new members. Which might account for not pulling out weapons to take down Agent May as they saw what she was capable of. I am thinking that "Sarge" just like here, even if not used in the US military anymore, is a sergeant and field leader for some other bossPerhaps he is a Coulson that was never recruited into SHIELD in his world that he came from. Hope they tone down the crazy girl cause it will get annoying real fast if all she says is that stuff about preparing for death. Lets call Sarge & his team transdimensional travelers who may have escaped from a prison of some sort in an alternate dimension and made their way into our world but who knows what or who they are looking for. Once we learn their agenda they will hopefully become more interesting & perhaps will join with the SHIELD team to take on a greater threat.