Meddex was a Caeliar scientist or engineer.
Meddex was assigned to work on the city-ship Mantilis while it was on the planet Erigol. A feedback pulse destabilized the planet and necessitated Mantilis' departure in order to protect several human Earth Starfleet officers and crew who were attempting a hostile action to allow the Columbia to escape.
The ship traveled a subspace tunnel, throwing it through space and time from the Azure Nebula in 2156 to Arehaz in 4527 BCE. Along with the other eleven Caeliar aboard, Meddex began to lose cohesiveness away from the quantum field of their planet, becoming one of them to forget what simple things like twilight were. As they became concerned for their existence, fellow Caeliar Felef considered consolidation of their catoms; Liaudi and Meddex were concerned how they would decide who would surrender their energy to the gestalt. Ashlok had already made an analysis of how to achieve greatest return from the least amount of sacrifice, and determined that any sacrifice would inevitably feel arbitrary, and it would be best to allow consciences to guide rather than a tyranny of numbers. Ashlok later gave up or lost catoms to ensure continuity of the gestalt. (ST - Destiny novel: Lost Souls)