Ah, valar morghulis / valar dohaeris, the two sides of the coin of the Faceless Men. I agree, the concept of “all men must die / all men must serve” is one of the more interesting repeated themes in ASOIAF. “Valar morghulis” was first spoken to Arya by Jaqen H’ghar in ACOK, and though we didn’t get a translation until ASOS (and Arya didn’t until AFFC), she nevertheless subconsciously understood its meaning, adding it to the end of her nightly kill list. At the end of ASOS Arya learned “Valar dohaeris”, the response, though again we didn’t receive a translation until AFFC. (I occasionally wonder about the early days of the ASOIAF fandom, what it was like for them to speculate for five years about the meaning of those words.)
Besides the High Valyrian words themselves, the concept of valar morghulis itself comes up in all kinds of places, such as the song “The Dornishman’s Wife” and Ygritte’s words to Jon Snow. (“And if we die, we die. All men must die, Jon Snow. But first we’ll live.”) In both those cases the idea given is that death is inescapable, no matter what — so it’s best to live while you can, take pleasure in the moment. Missandei expresses a similar sentiment, when Dany warns her that she may die in her service; “valar morghulis”, she replies — since everyone dies, it’s better to live in a dangerous situation as a free woman than live in safety as a slave.
But valar dohaeris is not quite the opposite of “all men must die”. It doesn’t translate to “all men must live”, but rather that they must all serve — must work for others, whether for other humans or as an instrument of the gods. This most likely comes from the origin of the Faceless Men among the slaves of Old Valyria; the first Faceless Man believed he was an instrument of the Many-Faced god of death, and freed the slaves from their bondage with the gift of death. (It may also be a literary reference to the Biblical curse of Adam: that humanity must toil to produce food until the day they die.)
In practice, valar dohaeris is given as a response by a Braavosi to any Faceless Man — and they will do their best to serve, and only beg that the assassin remember their name in return (for a Faceless Man is not allowed to kill someone he knows). As for other references within the books, it’s less obvious than for valar morghulis, but the feudalistic nature of Westerosi society does have everyone serving someone, and the characters are often motivated by their duty. A more subtle reference may be the game of thrones itself, in which everyone is a player or a piece. Even the principle of the game, “you win or you die”, may express the dualistic nature of valar dohaeris / valar morghulis.
Now, many characters exemplify these themes. But in my opinion, one of the best ways to look at it is through the Stark sisters, Sansa and Arya (two sides of the same coin). Both girls, on their paths through the story, encounter people who act as examples, as teachers to them. (Interestingly, some of these are the same people.) Sansa’s teachers show her the ways of valar dohaeris — of service, of duty, and of the game. (Ned Stark, Sandor Clegane, Cersei Lannister, Dontos Hollard, Tyrion Lannister, Margaery and Olenna Tyrell, Petyr Baelish, etc.) Whereas Arya’s teachers demonstrate valar morghulis — that all men must die. (Ned Stark, Syrio Forel, Yoren, Jaqen H’ghar, Beric Dondarrion, Sandor Clegane, the Kindly Man and the Waif, and others.)
Another fascinating aspect of this dualism is that their mother, Catelyn Tully Stark, can be seen as the coin that the girls are the two sides of. (See also.) Catelyn, in life, was the perfect exemplifier of valar dohaeris, of duty and service. But as Lady Stoneheart, she has become valar morghulis incarnate, a dead woman granting death as justice. It should be interesting to see how these aspects of the coin interact if ever they meet each other once again…
