#cherubs!

Lots of people just wrote in with "cherubs, how do they work!"

Like ten, by a quick count. 

Since there are a lot of more specific things you could think about with cherubs, I'm going to run with just one part, which is the body sharing swap, which I cannot be assed to go into canon to check if it's a peculiarity of the Calliope and Caliborn situation but igaf,* I'm assuming that this is a species that has radical personality shifts** in tune with their circadian rhythm.

From a biological standpoint, it helps to discard the sarswapagus as a bit of cultural baggage, and clearly they can swap outside of it because of the name thing.

Parasites are kind of a cheat (and I have used them a lot), so let's say that the shift is like, along with the 48 hour circadian rhythm of the cherub.  Tons and tons of animals have biological clocks, plants have biological clocks, and they can time anything from a couple of hours to a couple of months and file the information away for later when it will be useful.  Anyway in cherubs its regulated by a kind of dual hormonal system in antagonistic relationship.

This hormonal cycle is very stable and synched up with the lifespan of the cherub's erythrocytes!  

Human erythrocytes cycle like, every 3 months or so, and cannot live longer  than that because they lack a nucleus and therefore can't do important things like make new proteins.

Cherub erythrocytes have a life cycle of like, a couple of days, because they are unstable cell fragments or something.  The erythrocytes are produced by two lineages, the red one and the green one, and have different pigmentation (and different isozymes*** of the oxygen carrying protein.)   So there's a transition between the two populations of cells that's kept in sync by the daily (or whatever) hormone shift.

A whole bunch of brain and blood chemistry alters with the switch (like, uh, a bunch of receptors on different cell types notice the hormone shift and there's a massive kinase cascade), which is maybe an evolutionary holdover from cherubs beginning on a planet with really intense differences between day and night, or an extremely short year, or something that necessitated two very different strategies within each organism.

Xenobiologist for Hire asks are currently closed!

*"It's idiosyncratic magic," while sometimes a more fun answer, pretty much ends there and there is nothing to dig into.

**i think the idea that Calliope and Caliborn are the same brain with different chemistry is pretty interesting, I bet that memory storage in cherubs is totally different from human biology.