She’s willing to do just about anything to become more powerful as a necromancer. Just short of hurting her sister, she doesn’t care what she has to do. If it helps her, she pays no consideration to anyone hurt by the consequences. After consuming Naberius’ soul and attempting to merge with to become a lyctor, she acts frustrated that he won’t go along with it despite the fact that she just murdered him.

While Coronabeth is the more sociable sister, Ianthe does know how to be charming when she needs to be. She tends to be very sarcastic and witty with others, being able to strike up casual conversation. Even with people she has wronged. She still keeps up casual conversation with Harrow even after she effectively lobotomized herself.

As stated before, she only cares about herself and her sister. Her love of Coronabeth is the only genuine connection that she has and she would lay down her life for her if the opportunity arose. Everyone else, on the other hand, not so much. As mentioned with Naberius, she only saw him as an ingredient on her path to becoming a lyctor rather than a person. Even with her sister, she doesn’t fully understand her feelings since Corona would’ve undergone the process willingly and got upset when she wasn’t chosen. It seems she doesn’t have much understanding of what a healthy relationship is.

She also enjoys messing with people as well. Messing with Harrow’s hair follicles during the lobotomy shows one subtle way she does this. It also leads into her opportunistic tendencies. She went to Augustine for training, but when he tried to kill the Emperor and had a chance to save one of them, she chose the Emperor since it would be better for her.