Avian "Coke-Bottle Glasses" was a member of The Covenant who worked very closely with Elena Derevko. He was an expert in hacking and explosives.
Avian was sent to Amsterdam to observe a meet between Milos Kradic and Linus Halsey, where he wound up finding out that Vaughn captured the real Halsey and replaced him with Dixon. Later, Avian told Aleksander Petrovich, one of Kradic's men, that Dixon was working for the CIA. After Raimes took the blame for Dixon, Kradic and his men traveled to Vienna to collect a weapon called Hydrosek. Avian later called Elena and told her what happened, saying he wouldn't fail her (A Clean Conscience).
Avian showed up at the club where the meet took place and planted bombs inside, killing the Hydrosek sellers and almost Sydney. The two engaged in a long fight, which ended in Avian fleeing from the club without the Hydrosek. Elena later chastised Avian for his failure and he had to find a way to acquire it now that it was in APO custody. He traveled to Sydney and Nadia's house to hack inside Nadia's laptop, where he downloaded the files regarding the weapon.
Avian and Elena went to APO Headquarters and ambushed some of the security guards, quickly gaining access to the vault. Avian broke through the lock on the safe and Elena took out the briefcase holding the Hydrosek. Moments later, Weiss and Nadia entered the vault and found the Hydrosek gone...and Avian lying on the floor with his throat slit (Mirage).