As Flugel's apprentice, Shaula is absolutely loyal to Flugel and has never refused him once. Shaula has mentioned several times that she is in love with Flugel.
As Shaula is horrible at telling people apart, she refers to people based on smell alone. Due to Subaru apparently having Flugel's scent, she believes him to be her master.
During Meili's stay at the Pleiades Watchtower, Meili becomes attached to Shaula, who she refers to as "naked onee-san". Typically, she spends her time hanging onto Shaula's shoulder.
The author hinted at Shaula being a demon beast created by Daphne. This would mean Daphne is the mother Shaula was refering to so often. She repeatedly showed love and respect towards her and her Master.