On the topic of Vermillion theories, we talked a bit about the Vermillion eye markings with Koneko ( @koneko-pi) yesterday.
So, we have the Fire Vermillions (with markings) and the Flower Vermillions (no markings). Papa Fire Vermillion and Papa Flower Vermillion were brothers
Which means that either the markings are not of Vermillion origins since the last name comes from the father’s side in both families, but instead come from Mama Fire Vermillion who married into the family, or… OR then the markings are passed down from the father in some strange manner. I was thinking that it could be an “eldest son” -thing (why? I’m just going to say magic which would be, and I do agree with you on this, in this instance, dumb.) So that said markings are passed on through the paternal lineage from the eldest son onto his children.
This I got from the idea that the eldest sons of the Vermillion Houses already have their earrings going on for them, so it could symbolize something. And serves a fun headcanon of the markings simply skipping generation in the Flower Vermillion family tree and be inherited by Kirsch’s kids, because genetics are weird. (Is it unlikely for this to be a thing? Yes. Very much so. But is it entertaining? A bit amusing at least.)
However, long story short: I propose that the eye markings actually come from Mama Fire Vermillion.