[Charomon]

Since Terwilliger himself had a good guess about who they were it is kind of obvious that it was Raven and the elves of Qintarra. They probably followed him without he knowing about it. Perhaps to keep him safe and alive or maybe to send some kind of message to the dark elves like "we have not forgotten you, don't do anything stupid". Another thought is that they maybe know the location of T'sen-Ang but are unwilling to speak about it.

If you ask Raven about her view on the dark elves she will say some cryptic things about not sharing her mothers view on the matter (or something like that). She is quite poor at hiding her hatred for the dark elves however.