In the “chaos is a ladder” exchange between Varys and Littlefinger in season 3 episode 6 this line came up in the dialogue:
Petyr 'Littlefinger' Baelish: You're so right. For instance, when I thwarted your plan to give Sansa Stark to the Tyrells, if I'm going to be honest, I did feel an unmistakable sense of enjoyment there. But your confidant, the one who fed you information about my plans, the one you swore to protect... you didn't bring her any enjoyment, and she didn't bring me any enjoyment. She was a bad investment on my part. Luckily, I have a friend who wanted to try something new. Something daring. And he was so grateful to me for providing this fresh experience.
Lord Varys: I did what I did for the good of the realm.
I'm curious, what was Varys referring to by that?
My question is, specifically, what action is Varys referring to here? It seems as though it's something unlawful or immoral that he has to excuse his actions to someone like Littlefinger. In the end justifies the means sort of way, if you will.