I've created it.
An OC theorem.
I dub it: The Vowel Theory.
"a, e, i, o, u,, & SOMETIMES y."
When creating a group of OCs, one might create a sub-member to add to it.
This is the "Y".
An example in media would be South Park, where the main group is Eric, Kyle, Stan & Kenny, with Butters sometimes joining in as a 5th member, but never being a full on permanent addition.
Y sometimes takes the sounds of E & I, (ex. Friendly, Sky), which symbolizes how sometimes this sub-character will act as a duo character with a singular member of the main group. For instance, sometimes it's just Butters & Eric.
I made this at 3 AM and it works.
I've made a scientific theorem.