He has brown hair and blue eyes.
He and his brother possess a telepathic link with each other, and can mimic other people's voices.
He and his brother are one of the "true eleven" at the end of Dowsing the Dead.
In Going to Ground, he reveals that he and his brother were asked to come and mimic Dax and Gideon's dads in order to allow the government to capture them.
The Teller Brothers were named after Ali Sparkes' children: Alex and Jacob.