Eugene (Josh McDermitt) wasn't, isn't, and will never be the kind of character to charge into a herd of walkers or human enemies guns a-blazin'. No, Eugene is a survivor of a different caliber, relying on his wits and resourcefulness to get by and make himself useful. He may have lied about being a scientist with the key to ending the worldwide pandemic, but he's smarter than the average bear nonetheless.
After being captured by Negan and the Saviors, Eugene decides to stay with them, comfortable under the wing of such a powerful group that treats him relatively respectfully. It takes Rosita (Christian Serratos) — who guides and protects Eugene in the early days of the apocalypse — to make Eugene realize what a fool he was to betray his friends and defect to the enemy. He gets to work on a plan that single-handedly brings his onscreen kill count from three up to 186.
Knowing Rick and Negan's forces are soon to come to a head, Eugene takes advantage of the latter's trust and sabotages the Saviors' weapons. So, when the two small armies finally come face to face, Negan's side is decimated when the guns all misfire. They don't all die on the spot, but because of Eugene, their ability to fight is greatly hindered, making Rick's job that much easier. Apocalypse or not, Eugene proves that "brains over brawn" still holds true.
