Gilflatl are demons originating from another dimension.
The Gilflatl demon has a particularly unique way of ensuring its supremacy in an environment. By releasing its venom in aerosol form, the venom simultaneously induces accelerated healing and mental disorientation in humans, leaving them unable to remember their initial encounter with it while making irrational and out-of-character decisions for up to a week after exposure, but also hinders the enhanced healing of other demon species.
Gilflatl on Earth
When a Gilflatl came to Los Angeles, it ‘infected’ Angel Investigations; while Fred suffered minimal exposure as the only injury the venom could cure was a cut on her cheek, Wesley Wyndam-Pryce and Charles Gunn were particularly enthusiastic about the opportunities its enhanced healing presented, and even Cordelia Chase was intrigued and restored despite her current part-demon nature, while Angel was left seriously hindered by the beating he had taken without his enhanced healing. He was ‘encouraged’ by one of the residents of the dimension where the Gilflatl originated to keep the source of their new healing secret from his friends out of fear that they would try and capture the demon for their own purposes, Angel’s weakened condition making him doubt himself more than he might otherwise.
Despite his concerns about his friends and himself, Angel was able to defeat the Gilflatl during a later confrontation, his friends collecting themselves in time to defeat the Gilflatl’s recently-hatched offspring ("Fearless").