She should have been slowly going mad over the past 3 seasons, rather than doing it over a couple... sure some people will point to her killing innocents previously but there was no real narrative based around her gradually going mental, she went from a bit annoyed to full on genocidal maniac in one episode lol
Defo. Fan theories and book hints have been pointing at it for years, to the extent that it was more likely to happen than not. But as with the last couple of series, the problem is with the pacing. She went genocidally mad faster than a season 7 trip between winterfell and kings landing




