It’s a little old, but Collider had a pretty good interview recently with Adam and Jerome Flynn about various aspects of Ripper Street. Apple readers will want to check the whole thing out, but, in this excerpt, Adam lays out his own theory about how he ended up on the Reid team.
I think we had this fantasy that maybe Jackson had been thrown in a holding cell one night and drunkenly starting diagnosing people in the room. They picked him up and, without meaning to, he started helping them out. Jackson must have gotten Reid’s attention, some sort of weird way. Because he’s boastful and a bit egotistical, he probably started showing off and it came to bite him in the ass. He’s dragged, kicking and screaming, into this little partnership. He’s a very reluctant helper.