Originally Posted by tiggerpooh:
“Sophia Myles cannot come back as Madame De Pompadour, as the character died in the initial episode she was in back in 2006.
If you remember, The Tenth Doctor went back to fetch her, and was told by her husband Louis whatever number he was, can't remember, that she had died.
If the Doctor did manage to get back to when Madame De Pompadour was alive to take her in the Tardis, he'd be crossing over his own timeline. As the Doctor has said before, he cannot do that, as it would create a fold in the fabric of reality, and a paradox would occur.”
Yes, she can come back. Even if you accept your interpretation of the "not crossing his own timeline" "rule" (something which has been broken already, several times) writers will break that "rule" if there's a good enough story to be had. Time
can be re-written.
The Doctor (10) only visited her at certain points in her life. As far as I can see there's nothing stopping 12 visiting her again between 10's last visit
before her death and her actual death, I don't recall anything said in 10's final visit, after her death, that precludes that.
Whether it would make sense dramatically is another question. It would be a bit too much like River's story in the sense that we've already seen her death and would devalue the emotional impact 10s post death visit.