Tyrion has always made a point of highlighting his intelligence, noting that even though he doesn't have the physical strength of his enemies, he has more than enough cleverness to make up for it. So . . . um . . . where the hell is that version of Tyrion? The Tyrion we've grown to know and love over the last eight years? Because I have to imagine that that Tyrion wouldn't have sold out Varys, one of his few remaining friends, to Daenerys in such casual fashion. After all, Varys was only acting for the good of the realm — he could see that Dany was about to embark on a path of fiery destruction, with the innocent citizens of King's Landing paying for her fury.
To be fair, if Varys was indeed attempting to poison the dragon queen, then Tyrion's act of betrayal would make a bit more sense. But we have to imagine that he would have been able to figure out a way to either smuggle Varys out, or discuss what the Master of Whispers was doing before it was too late. As it stands, Tyrion's decision comes off shortsighted at best and cruel at worst. The only silver lining is that, by the end of "The Bells," the look on Tyrion's face as he stares out into the smoking ruins of the city makes it clear that he's flooded with regret for his continued faith in Daenerys.