OMG the Tachonis children are named after the 8 bones of the neurocranium
1 frontal bone
1 ethmoid bone
1 sphenoid bone
2 parietal bones
2 temporal bones
1 occipital bone
Since they're in a 3-dimensional space there isn't necessarily a common "order" they are listed in, but occipital bone is the furthest lower back of the skull, and I've arranged the list above in roughly "front to back" which does place Ethrand as 2nd and Occtis as 8th.
So the "occ" in Occtis is not dressing up "Oct" or any 8-related meaning, it's fully just referencing occipital. Occipital means "back of the head" from the Latin Ob (in back of) + Caput (head). The word part ob can also mean "in the way of, against," (see: obstruction) and it's probably unintentional but fun that this source for Occtis's name can also be translated to "against the head" as in, Occtis rebelling against the head of his House.
Referencing the bones of the skull is SUCH a fun goth vibe for house Tachonis and their necromancy (even as I have to laugh at the idea of like... "and this is my cousin, Distal Phlanges").













