Currently the head of Eastern Europe, Etrius is an old and highly influential member of the Tremere, whose accomplishments date back to the very origins of the clan. Of Swedish descent, Etrius was apprenticed to Tremere himself during their mortal lives in the Order of Hermes. He lives in the Vienna chantry, which he chose as the seat of the clan, and is responsible for guarding Tremere during the frequent times when the clan head is in torpor. This guard duty is to be taken very seriously, as the Vienna chantry is under frequent attack by Assamite assassins who have sworn vengeance on the clan and are continually trying to kill Tremere and any other councilors they can find.

Like the rest of the founding Tremere, Etrius was brought by Tremere in 1022 to the lair of one Goratrix, another member of the Order of Hermes who claimed to have discovered the secret of immortality through his experiments. It was here that Etrius and the other loyal followers of Tremere were made into vampires; and Etrius for one was shocked and appalled at what he'd become, though his loyalty to Tremere has never wavered.

Etrius and Goratrix have been eternally at odds in their advice to Tremere, dating back to their mortal lives when the two mages were openly competing for Tremere's favor. Goratrix has always been highly impetuous and impatient, whereas Etrius is calmer and more cautious. His early position against the strong recruitment of new Kindred, due to his personal ethics, was a large stumbling block for Goratrix, who wanted to infect all the other mage Houses as quickly as possible. Rumor (which is strongly denied by all Tremere) has it that it was this feud between the two advisors which inspired Tremere to force the Blood Bond on all clan members, a rule which is scrupulously followed to this day. The other most noted feud between these advisors was their argument over Tremere's decision to commit diablerie upon Saulot, founder of the Salubri. Though Goratrix's advice was eventually heeded, Etirus worries about future consequences of Saulot's death to this day.

Etrius' crowning achievement was his role as Tremere representative during the creation of the Camarilla. (In fact, the Tremere used to try to take credit for the entire founding of the Camarilla, though they have since withdrawn this claim due to vicious rumors about the clan's previous machinations.) His work there is generally considered integral to the formation of this body. Also, he and Meerlinda were the original drafters of the Code of Tremere, the oath which all neonates must still swear to their elders.