Given the phonetic structure of Davoust, we can speculate on its potential meanings by drawing connections to similar names and words in various European languages:
In summary, while Davoust is rare, its speculative meanings could draw from themes of generosity, revelation, or being cherished, depending on the cultural and linguistic context one considers.
The thrust of this storyline is control. Davoust's clinical approach to the Sweep Team and herself. They are tools she uses to get the job done and relies on Rylan to keep them in line and be ready to do her bidding.
The Water elemental is the Pool is insane. Somehow it survived the torture of getting pulled into the physical plane via direct conveyance and escaped the Water City. Floating in the water and causing havoc as it went. It hates humans and wishes to cause them as much pain as possible. It sees in Davoust a way to that end. Davoust is a cold scientist, but not evil. The elemental and her merge and form an extremely dangerous pair.
Ruh'haddad in the Census Office dead drop, placing the appropriate lore in the appropriate place to influence Davoust and set things in motion. The page contains the forogtten Symbol of Water, and seeing it unlocks Davoust's nature.