4. The 'Chuck Cunningham' Solution
For those unfamiliar with the reference, in the first season of the American sit-com Happy Days there were three children in the Cunningham family; Joanie, Ritchie, and Chuck. Chuck was the eldest of the three and was rarely heard to speak, nor was he often seen completely in shot. Most of the time you just saw him from the neck down dribbling a basketball. In the beginning of the second season he just... sort of... vanished. No one ever spoke of him again. Reliable Authority says that they killed and ate him. His name has now become a shorthand for 'Important character who just vanishes out of nowhere and we just don't talk about again.' Obviously I'm working up to talking about Dodo. Notorious as the worst Companion departure in the entire 50 year run of the show, Dodo literally left the room after not feeling well in episode two, and in episode four her replacement says, 'Oh yes, Doctor, Dodo wanted me to tell you that she's totes awesome here and is going to stay. You should absolutely not verify this information by calling her.' (If you look you can see that in her purse she clearly has a leftovers container labeled 'Dodobratten'.) The point being that we, the audience, have some time invested in the characters. It's at the very least rude to just throw them away out of left field with little to no explanation as if they were garbage. There's an element of this in many of the 'married off' examples, but other noteworthy examples include Melanie Bush, of whom we'll talk further in a bit. And a brief kind word for Liz Shaw, arguable the most under-appreciated companion in the series' entire history. She had one thankless season of introducing us all to the new Doctor, Format, and color palette before she disappeared wholesale between seasons. Unlike Dodo they at least mentioned her absence - once - in the beginning of the following season.* *As a side note, there's been a very pleasant uprising in recognition of Liz Shaw as the incredible feminist role model that she was. She never mentioned feminism because the idea that anyone wouldn't treat her as an equal was simply laughable. She Owned, Liz Shaw did. Add to which, she rocked an incredible miniskirt because she was a grown person and could embrace her own sexuality in any way she damn well felt like, thank you.