Herid Fel tells Rand that the Snake people's riddle about cleansing saidin stated "sound principles, in both high philosophy and natural philosophy." (TPoD,Ch14)
Rand visits with Herid. Herid tells him that somehow the Dark One's prison will eventually be restored to complete the Wheel of Time. (LoC,Ch18)
Herid wanders off from the school and Rand yells at Idrien Tarsin because he is not there. (LoC,Ch28)
Rand and Min visit Herid at Rand's school. Herid is too confused by Min's presence to be of much help to Rand. (LoC,Ch50)
The next day Herid writes a note to Rand saying, "Belief and order give strength. Have to clear rubble before you can build. Will explain when see you next. Do not bring girl. Too pretty." Then he leaves to go fishing. (LoC,Ch50)
Perrin visits Rand's school looking for information on where Rand might be, but Herid Fel has nothing useful to add. (LoC,Ch53)