Complex sentence: Grant was in reality, a DVX operator, in cahoots with Natalie Dearborn, Luke Spencer's physical therapist whose real name was Natasha; she was also a DVX agent.
Split into simpler sentences: Grant was in reality, a DVX operator, in cahoots with Natalie Dearborn, Luke Spencer's physical therapist. Whose real name was Natasha, was also a DVX agent.