Significance of 'There was a time they called porridge “gruel.”'

Question

In Nalo Hopkinson's short story Shift, Caliban has a relationship with a "golden girl". At some point, Caliban mentions she is cooking oats. At an earlier point in the story he says

There was a time they called porridge “gruel.”

I have no idea how this fits into the rest of the story. The Wikipedia article about porridge explains that, "Historically, porridge was a staple food in much of Northern Europe, North Korea, and Russia." The Wikipedia article about gruel says that,

It is a thinner version of porridge that may be more often drunk than eaten and may not need to be cooked. Historically, gruel has been a staple of the Western diet, especially for peasants.

The article also contains a paragraph on the etymology of "gruel". That does not really help, nor does the article about oatmeal.

After analysing the story for answers to two other questions, I am convinced that it is too carefully crafted for this porridge remark to be meaningless, but I cannot come up with an explanation for its presence in the story.

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Addition: I don't know whether this is relevant, but in Shakespeare's works, "gruel" is apparently only used in Macbeth, Act IV, where the "Third Witch" says, "Make the gruel thick and slab". "Porridge" is used in The Tempest, Act II, scene, where Sebastian says about King Alonso, "He receives comfort like cold porridge.". The word "porridge" also occurs in several other Shakespeare plays (e.g. 1 Henry VI and Troilus and Cressida).

Answer 1

I’m not sure that the use of ‘gruel’ sustains deep scrutiny into the history of the dish or the term.

Although many sources state that it was a ‘thinner’ porridge, which leads to a general, ‘Oliver Twist’ influenced perception that gruel is always penitential in character, in fact it could be a very rich dish, such as this example with dried fruit, egg yolks, wine and sugar. The Scottish Language Dictionary also just gives the meaning as ‘porridge’, with no distinguishing characteristic of ‘thinness’

What I take to be it’s significance in the short story is that it is being referred to as a dated or obsolete usage to emphasise how long Caliban has been in the world.

Now porridge is called ‘oatmeal’, then it was called ‘gruel’. So the point is not that porridge used to be nastier, only that it used to have a different name. Times change.

Answer 2

Porridge, and the cooking of oats, is a theme that runs through the story, so this reference to porridge does not come from out of nowhere.

What did we learn from your research? That porridge is a thick dish, sometimes sweet, sometimes with more complex additions to make it savory. Gruel, on the other hand, is thin, watery (another ongoing theme), simple.

Thus, in this simpler time, when they called porridge "gruel", you were

lord of the land and the veins of water

you had an easy life, you could afford to be gracious.