Shall Fen Shall is a highly Skilled Warrior Fairy bought by Ann. Because he was born from Obsidian, he's always very dark. He also has a sharp tongue.
Although this is obvious, he has feelings for Ann. But he doesn't realize it himself.
In volume 2 of the light novel, more of his past with Liz is revealed. He loved her dearly, as long as she was happy he wouldn't mind if they had to separate. This was a contrast to Ann, where Shall was unwilling to let her go despite knowing she would have a stable and safe life if she lived in Hugh's castle. He didn't like the idea of giving away Ann to Hugh. Liz had also said that her love for Shall was not the same love he felt for her. So contrary to what Ann thought, Shall likely did not have romantic feelings for Liz.
Shall was asked to leave and never to come back by Ann. Despite this, he came and looked for her anyway when he knew that she could be in danger.