Billy Coen

Hey, Queenie! Feast on this!

Billy Coen was a convict that escaped in the Arklay Mountains after the military transport vehicle he was in was forced off the road and was destroyed by James Marcus. He escaped to the Ecliptic Express where he met Rebecca Chambers.

Background
So, you seem to know me. Been fantasizing about me, have you?

Billy was a Second Lieutenant in the United States Marine Corps with Force Recon, who, along with a team of Marines, were sent into hostile territory in Africa to attack a village used as a terrorist training ground. Unfortunately, the air drop was off-target, and as such the team had to march across miles of hostile terrain to their target objective. The heat, combined with enemy attacks, soon reduced the team to four, and when they finally arrived, they found the village was actually full of innocent civilians. In order to cover-up the incident, the government scapegoats Coen for the ordeal, claiming, "one marine panicked under the extreme conditions and unintentionally killed the civilians." Upon returning to base their superior and base commander, Samuel Regan, had Billy tried, court-marshaled, and sentenced to death. Flashback cutscenes in Resident Evil 0 imply that Billy never took part in the massacres, but he neither confirms nor denies taking part in it to Rebecca.

Arklay Region incident
Listen, little girl, if you haven't noticed there's some pretty freaked out things on this train. And I, for one, wanna' (sic) get out of here. I don't think we stand a chance of doing it alone.

En route to the base for his execution, the military transport vehicle used to take him there was forced off the road by James Marcus, and then Cerberus attacked and mauled the MP's guarding Billy, causing him to run for his life. Billy then sought refuge in the Ecliptic Express, a stranded train, where he meet Rebecca Chambers. Despite their radically different backgrounds, the two formed an alliance in order to secure their survival. The two use their talents to pass through many of the obstacles they faced, and discovered the Umbrella Corporation's secrets.

Both were monitored by James Marcus, who sent various creatures to subdue the two. Billy proved his loyalty by saving Chambers several times during the game, whilst Rebecca proved hers by saving him. Coen and Chambers eventually met Marcus. After revealing the details of his mortal demise, Marcus mutated into a Leech monster.

The two managed to temporarily subdue the creature, only to discover that a self-destruct protocol has just been activated, caused by William Birkin. Matters became even more complicated when the leech returned. In the final battle, Chambers exposed the leech to sunlight, thus making it vulnerable to attack.

Knowing this weakness, Billy acted as bait whilst Rebecca continued to open the roof further until there was no shade left for the creature to hide in. He proceeded to deliver a final shot, which instantly destroyed the leech. In wake of the destruction, Rebecca allows him to escape, by telling her authorities that he subsequently perished in the Arklay Mountains after their first encounter, keeping his dog-tag as proof. The two bid farewell, and Billy disappeared soon after, not seen again. However, upon returning to Raccoon City, Rebecca filed a report claiming that Billy had died during the initial attack that allowed him to escape, she goes on to request a suspension of the case which presumably allowed Billy a chance at freedom.

Trivia

 * Like Carlos Oliveira, Billy only appears in two Resident Evil games.
 * The large tattoo on Billy's right arm reads "Mother Love".
 * Billy escapes from the armored car after it crashes due to a pack of Cerberi. The crash breaks one of the cuffs off, effectively allowing him to escape, and they dangle from his hand throughout the entire game. In the ending, he simply takes them off and throws them on the ground.
 * To date, Billy, Carlos Oliveira, and Leon S. Kennedy are the only main characters in the Resident Evil series that have not directly met the series' main antagonist, Albert Wesker.
 * Billy has shown that he is quite skilled with playing the piano. Rebecca could not play it well at all in RE0, but she did figure out how to play it in the Spencer estate with time.