Here’s my request for the 50th anniversary. Actually, for any episode.
I want to know about the Doctor’s first wife. Who is this woman? How long where they together? Did he lose her before he took off for the universe or as late as the last Time War? Was she a Time Lady or a Gallifreyan with another type of service?
Did their child sleep in his baby cot? Is that why there’s at least one other inscription on it?
Did they argue over his desire to see the universe? Or did she understand by, like so many of his companions later on, she wanted home more and not that life?
During the Fifth Doctor’s time, fans had a theory that a reason why the Doctor was so hands off with his companions and other potential partners was because he remained faithful to his wife. The show never said.
She was a major part of his life, but we know nothing about her.
Personally, I imagine River coming across something and asking about her. Now, River has a big jealous streak — we’ve seen it and Moffat confirmed it again a few months ago — but it’s for someone the Doctor would be cheating with now, (when it looks that way - like his jealousy over Octavian) not just any person at all. She knows how important this woman was to him, how crucial she was in his life for centuries. (I’ve asked my husband about his first wife out of curiosity: how are we alike, how are we different, how they met etc.)
In my mind, River comes across the baby cot, notices the other wording on it, and asks him. The TARDIS probably put it right in front of her, to make sure her Child and the Doctor’s new wife, knows about the other important woman in her Thief’s life. After he first stays quiet on it, he finally talks about her.
It would add explanation to River’s look at the baby cot inA Good Man Goes to War; some of her fond memories is that day when he opened to her about someone he’s never talked about before.
(I also have head canon that somewhere in the Tardis are paintings of the Doctor’s loves with his first wife’s and River’s together on one wall, marking them as special as the Women Who Married Him.)