Rob Fortune, aka Cowboy (a nickname from Ryder, which he's not particularly fond of) was a surfer dude in LA. He was out surfing when he wiped out, and then found he could somehow grow gills and breathe underwater. His girlfriend, Tobi Frye, was actually "one 'a them stinkin' Skrulls". Ryder blew her away and exposed her true nature, then chased Rob down and wrecked his car. Ryder revealed the cause of his own recent changes to Rob, and he joined the group.
Rob has many reservations about actually killing anything, even Skrulls.
Rob can transform his hands/arms into different objects/weapons. He could transform into representations of other objects. Rob eventually gains some sort of control over his personal reality, able to phase in and out of any place and back at will. He claims he gained this ability after the Skrull DNA finally overcame the remainder of his human DNA, thus changing reality itself.