Commander Shepard can encounter Forvan at a bar when and order a drink from him. Shepard then falls unconscious and wakes up outside of Afterlife. A human passerby named Henner explains that Forvan has a grudge against humans and therefore poisons human customers — Forvan's brothers were stationed at a mining colony on Bekke when Jacob and his crew attacked it allegedly to prevent an attack on the Citadel by batarian terrorists. Following his brothers' deaths, Forvan now poisons human customers to "return the favour".
Shepard can confront him about his actions and take necessary measures against him. The Commander can loudly (and correctly) allege that Forvan regularly poisons the drinks he serves. Forvan pulls out an M-6 Carnifex and points it at Shepard, which leads to his execution by an irate turian bar patron who heard the accusations.
Alternatively, Shepard can force Forvan to drink from his own poisoned stock, which leads to the bartender's ironic death. Shepard can also threateningly state that Forvan isn't worth the Commander's time, letting Forvan leave alive with his vow of never doing it again. Regardless of how Shepard deals with him, Forvan will eventually be replaced by a salarian bartender whose wares are only threatening to Shepard's sobriety.