Street Fighter EX/D. Dark

Born in Germany, Doctrine Dark once served under the orders of Guile with his own special tactical reconnaissance unit. During his tour of duty, his own unit got into a bit of a scuffle with a rival unit, lead by Rolento. The minor scuffle escalated into a full-on battle, with both sides receiving heavy casualties. Doctrine Dark was the only member of his unit to escape. However, he was severely injured emotionally and physically. Outfitted with a portable breathing apparatus, he eventually escaped from the hospital and went into hiding, only to re-emerge as the deranged psychotic killer Doctrine Dark. Dark holds Guile responsible for the massacre of his unit, and seeks to kill Guile as a result. (The culprit was in fact Rolento, as stated in the game manual.)