Calsidiu is the apparent 'leader' of The Myreque. His two underlings are lieutenants Veliaf Hurtz and Safalaan Hallow - Safalaan leads the Sanguinesti division, Veliaf the Myre-resistance, and Calsidiu is their superior. Sani Piliu says in In Search of the Myreque that, as far as she knows, he is the leader. Calsidiu is currently missing, and his whereabouts are unknown as are any other details regarding his identity.
During Sins of the Father, Veliaf Hurtz reveals that Calsidiu is not a real person and does not really exist; and was made up to try and instill hope in the rest of the Myreque.
- The word Calsidiu is an anagram of the word suicidal, which may be what the resistance ultimately is.