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. Flugel in turn, was regularly exasperated at her antics, as she mentioned that he had said something similar when Subaru berated her.
After Satella's stamp, Reid would always come to see Shaula had been running away from Reid Astrea since was a womanizer, but compared to her running away from him, she confessed that she would rather Reid Astrea be a better partner than Volcanica.
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. She went as far as to keep the fifth rule of the Pleiades Watchtower (being allowed to destroy the trials) hidden from the Emilia Camp to spend more time to Subaru, showing her immense attachment to him.
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. While Shaula did think positively of her, she displayed little to no grief of learning the fact that she was murdered, stating that she only cares about Subaru.
The author revealed that Shaula is a Demon Beast created by Daphne. This would mean Daphne is the mother Shaula was referring to so often. She repeatedly showed love and respect towards her and her Master.