The idea behind Inconstant Companions (which I have stuck under Big Finish even though it applies to more than that – e.g. Sally Sparrow) is to celebrate the one-off (so far) performances of those that bring various adventures to life or add tremendous depth due to the sheer quality of the performance and/or the writing.
This will dip into TV but mostly stay in the Big Finish range.
The rules (which I shall ignore) are:
- Only appears once (e.g. Liv Chenka); or
- Appears more than once but not as a travelling companion (e.g. DI Menzies); or
- Travels in the TARDIS but only within one story.
There will be special note (e.g. Flip who is to join the Sixth Doctor) of those who move from inconstant to constant. Also I find that (so far) all the examples are female – this is either bias on my part or a reflection of the general case that companions have been female in most cases.
As to why inconstant it means variable which almost fits the bill and I like the word (from reading Larry Niven’s Inconstant Moon many years ago).