Most lighting problems are not equipment problems. They are distance, angle and subtraction problems. Before you add a second light, move the first one.
Start close. A large source close to your subject wraps softly and falls off fast, which gives you a dark, controlled background for free. Pull the same source back two metres and the whole room lifts — same light, entirely different photograph.
Then subtract. A single black flag opposite your key does more for shape than any fill light. Shadows are the subject; the light just describes them.
Shoot ten frames moving only the light. Keep the contact sheet. It will be the most useful reference you own.