Foundation 4 - Foundation's Edge by Asimov, Isaac

Hidden in her memories are the secrets to tracking down the last of Felecia's kind, the Greats; powers that have ruled since the beginning of time, now blending into the world around them, unnoticed. Or so they thought.

After the death of her parents, Nichole is faced with the daunting task of caring for her younger brother and sister. With a new job opportunity, comes interesting twists and turns, which lead her into an exciting new life.

Taus, a sentinel, is pushed to his very limits of self-discipline and focus when he finds Tru stranded in his realm, having fallen victim to an insidious race's curse. Encountering various mythical creatures in their travels, they traverse the dangerous magical realm seeking a cure to send her home.