I think a lot of River!
I admit I didn’t always. Back when she had only one appearance to her name in 2008-ish, my thoughts on her were basically “…she’s cool, I guess?” I didn’t really have much of an opinion on her. But then she came back to the show, which I assumed would never happen! And they developed her and her backstory, which I also assumed would never happen!
River is a very flawed (interestingly flawed) person but we see her learn and grow a lot – we just see it in the wrong order due to time travel – and it infuriates me when people say she’s just the love interest, just there for the male audience to wank over etc*, because she has her own arc and own personality and she’s basically a female Jack Harkness? Who everyone (rightly) loves? But anyway. I’m looking really really forward to seeing her at Christmas.
*This is extra galling because Doctor Who is a children’s show and River is, despite the occasional flirty line, a children’s character