Complex sentence: Patsy is something of a "dark horse" character; he has very little back-story compared to the other members of the crew, and relatively few lines, but visually he is very frequently present on screen.
Split into simpler sentences: Patsy is something of a "dark horse" character; he has very little back-story compared to the other members of the crew. He has relatively few lines, but visually he is very frequently present on screen.