INCOMING KH HEADCANON
you know a thing I’ve had in my head for a while is like, I noticed that out of the Destiny Island Trio and the Wayfinder Trio, Terra and Riku were alike in the sense that they had issues with their darkness, which isn’t anything new. But alongside that, I also noticed that they were the oldest within their trio and that got me thinking like…
Kairi’s Grandmother’s story mentions that light survived in the hearts of children (which we now know are the keykids who survived the KEyblade War), so what if like…children are more likely to have an abundance of light within their hearts? Like, the darkness is still there, but the light is just more prominent at that stage in life.
Now as they get older, that darkness starts to make itself known, so there’s an adjustment within the heart to keep a balance (it’s alllll normal, nothing wrong with that). It’s just…not everyone has an easy time through this stage of life and that balance kinda differs from person to person (it’s like puberty, shit happens and you’re either fine or ready to throw yourself down a flight of stairs). Pair that up with negative attitudes with darkness and you’ve got yourselves a situation like Terra’s or Riku’s (or if you wanna go about it a different way, you have Master Xehanort and Eraqus and Xehanort is kinda the oldest out of the two of them).
So with that in mind, apply that to the keykids, who are likely to come in various ages (still within the range to be considered children by adults). No two keykids are the same, so when that process starts to happen, you can only imagine the sorts of issues that will pop up and of course, you’ll likely have some keykids who are especially vulnerable…
And vulnerable keykids make for easy targets, which can result in the creation of Darklings. So basically Darklings are keykids (older keykids especially) who were having issues with their darkness and had little to no guidance on how to deal with it, resulting in their untimely demises.