I think Clarke will be mentally strong enough to resist Josephine from within. Also, I wonder if we will "hear" Clarke's and Josephine's conflicting thoughts, like in Stephanie Meyer's The Host. Maybe Josephine can also feel Clarke's emotions, and will start to feel bad she "stole" somebody else's body. Who knows, maybe Clarke can convince Josephine to help put an end to the stealing of people's bodies by the Primes. It would be very awesome to see Clarke and Josephine work together, like Wanda and Melanie in The Host.