Originally Posted by TorchyTD:
“ but then a random idea came up- what if it isn't 10 River knows and loves, but 10.5?? Do you reckon it could be possible?
Anyone got any thoughts on this?”
Not possible.
River knew about Regeneration and that the Doctor could do so.
Given that the Doctor rarely talks about regeneration unless it's about to happen to him it's likely that River has witnessed at least one.
10.5 of course can't regenerate, so unless for some reason he claimed to River that he could she would have no idea about regeneration nor expect that 10.5 could do so.
While it's clear* that River did know Doc#10 it may only have been for a few encounters (the ones she mentions from the diary plus a few more maybe) her "main" Doctor (and maybe even the Doctor she first meets) could be Doc#11 or higher.
Some people are speculating that since we have not been told her Characters name Karen Gillan is in fact a young River Song.
Personally I can't see it happening but it is curious why we weren't told a name.
Was there a gap between Freema being announced as the companion and her character name being announced (pretty sure we were told Billie was playing Rose Tyler straight away), I can't recall?
If there was a gap then this is just following form but if this is the first time they've done this they must have a reason to keep the name unknown.
*Even if what was shown/said on screen is not enough to convince some people SM himself has said she had met Doc#10 previously.