she's lacking something that would make me believe anyone would find her threatening.
I agree, and I do actually rather like RLC. There is something both in her performance and, I'm sorry to say, the way she's been written so far in the context of the relationship with Daniel that hasn't allowed her to really be a strong counterpoint to him that she needs to be for the show to work IMO. Sometimes she's great - I loved her diving off the fire escape and cuffing a perp in the pilot - but other times it's like she's an entirely different character. :/