>>149403820
Poet, revealed in a QNA and then mentioned only and only given one piece of end credit art.

My favorite theory is Viren is really his father and Damian is completely fabricated. Think about it; died before he (Callum) was born, had a "breathing sickness", his mom would never talk about him and Harrow never met him. Sarai apparently told Callum that everything Damian did was taxing and made him breathless so baby making would nearly be impossible.
Callum has the same hair, chin and facial structure as Viren.