Here's one thing I never understood. Why did Donna have to leave? Don't get me wrong, I understand in the show why it had to happen. It was a fabulous but bittersweet episode. I cried. Just the reactions for Donna and the things Wilf was saying; they got to me. Character-wise, I couldn't stand what had happened to Donna, and it was one of the most tragic endings for a companion ever (at least in my opinion). Series-wise, it was as brilliantly written as it was tragic.
But there must have been a way to save Donna other than wiping her memories and reverting her back to before she'd met the Doctor. Personally, I always end up at the Chameleon Arch. As we see in "Human Nature", it rewrites a Time Lord's biology, every cell, to mimic that of another species. If Donna is part Time Lord, then hypothetically it could work on her, and even still, I'd like to think the Doctor could probably reconfigure it to work. But anyways, why couldn't they use that (assuming it could be made to work) to rewrite Donna and remove her Time Lord knowledge and biology so as to stop her from burning up and dying?
Like I said, the story was wonderfully well written, and this mostly just comes from my constant ponderings about possibilities since Donna was my favorite companion and I hated to see her go. (I know the season is long since aired so this may seem late, but Partners in Crime was on today, so I was thinking about it again.) And hey, feel free to comment beyond just Donna, if there are other solutions you were wondering about for other bits of story.
EDIT: We went off track and started talking about the goods/bads of the companions, mostly current but also as compared to the past. It's a more interesting discussion than the original topic, so I'm changing the topic title and we're continuing on.
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