The Black Cloud (metaphor)
When discussing Albus with Harry, the centaur Bane describes a "black cloud" around his som. Albus is not actually surrounded by a black cloud; instead this is a metaphor for his own isolation and unhappiness. Harry interprets this black cloud to be Scorpius Malfoy.
Love Blinds (metaphor)
Dumbledore warns Harry that his love for his son has blinded him. Harry's need for Albus to be safe and happy ultimately does not allow him to see his true needs and causes him to further their rift.
The Scorpion King (metaphor)
Scorpius's new nickname illustrates his rise to a new social stratosphere in the alternate-reality future. Though not actual royalty, Scorpius rules the school was though he is, providing a contrast from his outsider status in his previous life.
Mudblood (metaphor)
This derisive name for Muggle-born wizards uses the cruel metaphor that their blood is unclean to draw a distinction between those of full wizarding blood, or "pure-bloods." Scorpius Malfoy learns that in the future, Mudbloods are tortured and even killed for their lack of magical ancestry, and are only referred to as Mudbloods, rather than Muggle-borns.
Scorpius "Planting the Acorn" With Rose (metaphor)
Scorpius claims that by asking out Rose, he is planting an acorn of pity that will eventually grow into the "tree" of their marriage. The acorn represents the bit of pity that she has for him. By Scorpius's logic, at least she has feelings for him in the first place, and therefore they could change and grow.
