Neverseen

You might be looking for Keepers of the Lost Cities Book Four: Neverseen.

The Neverseen are the rebel group opposing the Black Swan. They are also the ones who started the fires in the Lost Cities and kidnapped both Sophie and Dex.

Mark of the Neverseen
The Neverseen wear a patch on their cloaks. The patch is a white circle with an eye in the center.

Known Rebels
Brant: Brant is the pyrokinetic who burned Sophie and killed Jolie.

Fintan: Fintan taught Brant how to summon Everblaze. His mind was broken due to a memory break.

Lady Gisela: Gisela was one of the lead rebels and also try to kidnap Silveny. Keefe threw a ninja star at her, giving her a scar at the beginning of book 2.

Ruy Ignis: A Psionpath who attended Exillium

Many Dwarves

Alvar Vacker

Keefe Sencen : As of the end of Neverseen

Characters believed to be in the Neverseen but not proven to be so:
Quinlin Dame Alina Alvar's Friend Lord Cassius