"Like the Augurey insists – the future is ours to make – so here I am – making a future – with you. For Voldemort and Valour."
-- Polly Chapman (CC3.2)
In an alternate timeline where Harry Potter died at Battle of Hogwarts (arising from the use by Albus Potter and Scorpius Malfoy of the Experimental Time Turner), saying this watchword or slogan is combined with putting a hand to the heart and then touching the wrists together.
Scorpius Malfoy hears the slogan used by Dolores Umbridge when he is called into her office (CC3.1), by Polly Chapman after she has asked him to take her to the Blood Ball (CC3.2) and by his father Draco when he goes to his office at the Ministry of Magic (CC3.3). It is only during this latter visit that Scorpius manages to say the phrase aloud in its entirety himself, having fudged it the other two times.
Like many mottos or phrases of this type (eg "For God and country", "Cry God for Harry, England, and Saint George!"), the main purpose of its use is to bind a group of loyal followers together. Coupled with the hand motions, this has a similar feeling to the Nazi salute performed by followers of Adolf Hitler.
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