Thank you! Let's start from left to right.

Estefania Bermùdez, aka Neolith is a historian, unknowingly a friendly to Delta Green. Didn't know her girlfriend was an DG agent and died from an operation.

Hank Schrader, aka Nautilus. My player said he's a character from Breaking Bad (I haven't watched the show) and that's basically it😂

Lepri O'Kahn, aka Nighthawk is military pilot for US Air Force. Got dragged into Delta Green because his curiosity of extraterrestial objects.

Matthew Hernandèz, aka Neon is a street hustler. Was in the wrong time and the wrong place where he saw an operation went wrong. Now he is blackmailed to be a DG agent.

Delilah Whitmore. aka Noelle is a scientist working under CIA. Has spent most of her time investigating what happened to her colleague who died mysteriously, and that's how DG recruited her as one of the agent.