For the past five years or so, they’ve been working together writing music for films and podcasts. They also created the music for a new scripted podcast, “Star Trek: Khan,” focused on one of the great Star Trek villains of all time, also released in September. The drama follows Khan’s story leading up to the 1982 film “Star Trek II: The Wrath of Khan.”The podcast is directed by Fred Greenhalgh, a longtime podcast writer and producer who lives in Alfred. Greenhalgh said the music plays a critical role in “Star Trek: Khan” because it helps create images in a listener’s mind. The director of the film, David Altrogge, had heard music Marcus wrote for a podcast called “Conviction: American Panic” and was impressed.