Is there any character or group of characters that you wish they could have done more, said more or "been" more, by the time the series ended ?
Let's say you take your favorite series that have concluded, as in "ended normally", "is waiting for a sequel" or "[sadly] got cancelled", and pick your favorite character. Did you ever wish something particular would happen to that specific character, but in the end, didn't ? Did you ever said to yourself: "Aw, I wished she could have said that to this character." or "Damn, he didn't get to do this afterall." ? I'm saying for series that have been concluded, but on-going series can definitely work too, as you could state your expectations for your favorite character(s) in future episodes or chapters.