In Listen we learned that Danny was in fact Rupert Pink. What was supposed to be a trip into Clara's childhood turned out to be the trip into the childhood of the man with whom she now shares a connection. A place where the Doctor's nightmare manifested; a children's home in Gloucester where orphan Rupert Pink sat alone on his bedroom floor, fearful of the thing lurking under his bed. The death Danny faced as a solider was only part of his troubled life. In Listen we were given another question to ask about Clara's new potential love interest. What happened to his parents? Between that and the mystery of his actions prior to coming to Coal Hill School, Steven Moffat has created a lot of potential in this new character. Uncovering those mysteries, seeing his relationship with Clara develop and the inevitable meeting between the two men in Clara's life; there's plenty more to come from Danny Pink.