Role in the series
Setsuna starts out as a cold and isolated girl, loyal only to Moebius and acts sly. When she, as Setsuna, meets Love, Love's nature and the "happiness" shown to her at first was seen as nothing, but over time she slowly began to open to the girls and eventually her heart, cracking piece by piece to them but was too stubborn to realize it. She refused to admit that she had a weakness and would throw a small fit before storming off when annoyed.
After switching sides, she seems to have lost most of her stubborn mind, and is typically sweet, reserved, and patient. It is suspected that this is out of guilt over her past sins and honest naivety. With the girls help she is able to get over this while remaining sweet and kind to them. She also retained her wise nature and put this to good use during fights.