Selecting one line took me a long time, to be quite honest, but I finally settled on these from MacBeth, Act V, Scene V:
I have almost forgot the taste of fears;
The time has been my sense would have cool'd
To hear a night-shriek; and my fell of hair
Would at a dismal treatise rouse and stir
As life were in't; I have supp'd full with horrors;
Direness, familiar to my slaughterous thoughts
Cannot once start me.
In the play, MacBeth is waiting for his enemies to attack when he hears screaming from inside the castle. He explains to the audience that he's become so accustomed to doing terrible things that he is no longer easily frightened. The irony, of course, is that the outcry is due to his beloved wife, Lady MacBeth, having killed herself out of guilt for the murder they performed together. The irony of these lines would work for Gerard Argent just as well.
It might seem strange, but Gerard and MacBeth have an especially important thing in common: they often claim that their murderous actions are impelled by outside forces. In MacBeth’s case, the Scottish lord betrays his king and his dearest friend, even though he knows these actions are wrong, because he can point to the ironic prophecies of the Three Witches.
Gerard doesn’t have anyone supernatural oracles to blame his actions on. Instead, he insists that the Argents are at war with the supernatural. Whereas the Code argues that the Argents should only hunt in response to violence ("We hunt those who hunt us"), as embodied by Chris's interpretation, Gerard steadfastly rejects that position. He announces in Omega (2x01) that he's going after every one of them because they killed Kate, despite knowing that isn't his real motivation or that Kate struck first. After sharing the parable of the Scorpion and the Frog, he declares he "know[s] a werewolf's nature" in Visionary (3x08). He declaims on La Bête's murderous tendencies in Damnatio Memoriae (5x12) as if it were an exemplar of a werewolf rather than just another serial killer.
Derek, in a way, is wrong. Gerard isn't declaring war at the beginning of Season 2, because he acts as if he's always been at war. You can see him calculating the use of cutting down the Nemeton (though we don't know for sure he did it); he orders Kate to destroy the Hales, innocent children included. He speaks in strategies and military terms. He quotes Sun Tzu as often as he does Shakespeare. His argument is clear that war not only justifies his family doing terrible things but demands it. "When it comes to survival," he announces in Master Plan (2x12), "I'd kill my own son." He argues that Allison, too, must ready herself to do terrible things because "She'll feel the ground shifting beneath her feet time and again in her life. It is our job to teach her how to keep standing" in Party Guessed (2x09). His first mission for his 18-year-old son is selling weapons to a criminal organization without telling him in Silverfinger (3x17).
One of the keys to note is that, also like MacBeth, Gerard doesn't regret this, not in the way that say Chris and Victoria do like when they wanted Allison to have a choice. In fact, he takes pride in the strength of his will, as the Scottish king has forgotten fear. He gloats when he thinks he has Scott on the ropes about his ability to get things done in Battlefield (2x11), "and if you haven't noticed, I have a very impressive means to motivate people." Even when defeated, he remains confident, as he boasts to Allison and Scott, "I don't go easily, though, do I?" He's proud of his actions as he shares with Liam in The Sword and The Spirit (5x14) "they would call me a necessary evil, but you can call me Gerard." He wants to transform his wicked violence into a legacy through the lens of war and necessity; his entire story in 6B is Gerard trying to reframe his terrible deeds as a legacy. Even when he's making a deal with a demon, the Anuk-Ite in Genotype (6x18), he's triumphant: "The legend is, is that you need silver to kill a werewolf. The truth? You need an Argent."
While both MacBeth and Gerard try to position themselves as not as other men, their ends are the same. They are not kings or generals; they're monsters. "Turn, hellhound, turn!" MacDuff cries to MacBeth at the beginning of the decisive battle, and Chris Argent condemns his own father; "If you're looking for rationality, I think he left that behind a long time ago." These men have talked themselves into evil, and they pay the price for it. They both pay the price for it as well. MacBeth, motivated by prophecy to do wicked deeds, doesn't think that prophecy can be against him, but it is, for Birnam Wood does come to Dunsinane. While Gerard, who always saw the interaction of supernatural and human as a war regardless of the individual participants, is destroyed by someone he refused to see as his own daughter.
The final irony would be that Gerard would quote MacBeth as part of his arrogance and vainglory, because he stands apart from other humans as one who hunts monsters, but like MacBeth, he would fail to see that his own arrogance caused his destruction.
