Doctorwhovian
Fleet Captain
Similar to Emperor_Tiberius's poll about the regeneration stories, Not sure if crossover's the right word, but what I mean is, companions that travel with two incarnations of the Doctor, before and after his regeneration. In some cases such as Tegan, Nyssa, Peri etc. I think the new companions were introduced to help ease in the new Doctor (with some continuity to the previous incarnation) or be his main companion, as they appear in the last or next to last story. Other times it's not as planned, but the companion sometimes goes through some character changes as they adapt to the new Doctor, such as Sarah Jane, Rose, Clara...or in the case of Mel and probably Ben, Polly and Adric, the old companion doesn't quite gel with the new Doctor and is written out, replaced with a new companion more suited to the current incarnation (Jaime, Ace etc.)
I'm not really including Grace, Jack or the Brig and UNIT though. Kind of forgot.
I'm not really including Grace, Jack or the Brig and UNIT though. Kind of forgot.