Daniel is a side character whose first on-screen appearance as himself was at the end of Healthy Eating, in which it was revealed that he had been playing the Fake Slenderman from the first few videos. The Hybrids state in the video Public Service Announcement that they have no plans to parse the videos and point out to the audience which appearances of Slenderman where real and which were faked, so we will probably never have confirmation about which appearances are Daniel and which are the real Slenderman.
Since his appearance in Healthy Eating, Daniel was not seen on camera until May & June. In the description for the video "Ryan & the SEVENTRIALSOFHABIT", it is mentioned that Daniel loaned the EMH crew his camera with night vision. During the 11/26 UStream, they revealed that he had actually been present and was holding the camera.", it is mentioned that Daniel loaned the EMH crew his camera with night vision. During the 11/26 UStream, they revealed that he had actually been present and was holding the camera.
Daniel had begun appearing as a background character in a few videos since the video, "May & June". Most of the videos that he has appeared in are centered around holiday gatherings like July 4th and Christmas. Following that tradition he appeared in the video Next on Christmas 2012, where he was killed by Evan/HABIT.