Betrayal

Sontaran Commander Stenck acknowledged that he was committing the "ultimate betrayal" by releasing the Lupari shield which he had previously promised as a means of protection for the Daleks and the Cybermen from the final Flux event, resulting in the destruction of their space fleets. Indeed, the Dalek War Fleet, upon seeing that the Lupari ships were reforming, observed "this is a betrayal". (TV: The Vanquishers)

The Twelfth Doctor considered Clara Oswald to have betrayed him when she attempted to force him to undo Danny Pink's death, though he noted he cared for her enough that betraying him made no difference in their relationship. (TV: Dark Water) In an alternate timeline however, the Twelfth Doctor did not forgive Clara for her betrayal, evicting from the TARDIS, though he eventually forgave her and came to regret his decision. The alternate Twelfth Doctor, knowing his timeline should not be, attempted to brainwash his past self not to forgive Clara's betrayal, only for a past version of Clara to convince him to halt his scheme. (COMIC: Four Doctors)