Who is "we" in Franks' monologue?

Question

Episode 10 of the 4th season of House of Cards contains a fantastic scene of Frank intimidating Catherine Durant.

When referring to himself Frank initially uses first person singular:

But of course, it makes sense that they would've haunted me because it's all true.

-What is?

-Everything Lucas Goodwin claimed. I killed them both, just like he said I did.

But then he switches to plural:

But of course, nobody believes it, and nobody ever will. Because that's how good we are at making things disappear. No, we didn't kill anybody. But we would have if it was necessary.

Who does he mean by "we"? The special forces that he is superior of? Some mysterious group of people behind him in existence of which he wants Catherine to believe? Him and Claire? Or maybe he's using pluralis majestatis to increase the impression?

Answer 1

Frank is spilling the beans to Cathy. The only reason he chooses to do so is that he knows that Cathy can't prove anything he said; nor can she really go in against him.

Frank made Cathy's career. Although she was in the dark about the grand scheme; she has unknowingly been an accomplice to a lot of things Frank has done.
This isn't unique to Cathy. Frank has roped others into his plans, some willingly (Claire, Doug), some without their knowledge (Cathy, Donald Blythe, Seth).

So you could interpret his usage of the plural in several ways:

• We = Frank and Cathy (and possibly others, through implication). Frank is communicating that Cathy is considered an accomplice and she cannot turn on Frank without taking herself down.
• We = Frank and unnamed others. Frank is implying that he is not working alone, and that Cathy will not be capable of going up against all the conspirators.
• We = Frank and Claire. Frank is communicating to Cathy that Claire is part of the conspiracy and Cathy cannot just run to Claire to reveal what Frank has been doing.

My interpretation is that Frank means him and Cathy. He is showing Cathy that she is tied to Frank. Both politically and criminally. Though she never knowingly committed any crime, Frank will be able to take her down; if not pass most of the buck to Cathy. All Frank needs to do is claim that Cathy was aware of the conspiracy, and Cathy can do nothing to prove him wrong since her actions can be interpreted (in hindsight) to indicate she was aware of the situation.