Parker Theroux

 was an alien pilot.

When their ship got shot down, he and Melody Quartararo escaped. They adopted human identities and got government jobs, eventually becoming CIA agents. They investigated unusual cases in hopes of recovering the Stormcore so they could repair their ship and leave.

Unfortunately, to prevent an an extradimensional ice creature from expanding across the Earth and destroying all life, they had to destroy the Stormcore. (PROSE: Drift)