4. The Doctor Will Save Someone At The Cost of Shortening His Own Life
2006s
Rise Of The Cybermen saw the Tenth Doctor repower his close-to-death Tardis by using his own life force to recharge a small part of it that was still alive. The catch was that it knocked ten years off his life. Trailers for
The Angels Take Manhattan show a small amount of orange energy passing from the Doctors hand to a womans hand he holds it. As soon as this trailer hit the internet, there were immediately theories that somebody would regenerate, and (much more bizarrely) that Amy and Rory were Time Lords. A less idiotic but still out there theory is that whatever happened to Amy at Demons Run in Series Sevens
A Good Man Goes To War left a small amount of regenerative energy in her. Of course thats not what this theory is about. My moneys on somebody being wounded or having something timey-wimey happening to them that the Doctor attempts to reverse by passing some of his life-force into their body, clipping a few years off the end of his life.