Ai wears a mask of cold personality. Even in situations in which are emotion-evoking, she doesn't appear moved in the least. Additionally, Ai is oddly silent and serious. She seems to only chat when the need arises, rarely speaking simply for the sake of it. In the event that Ai does talk out of ordinary circumstances, it is about something in which she believes is necessary for someone to know, or to correct somebody where needed. The main reason for her introverted personality is suspected to be a result of her having grown used to silence.http://hell-girl.wikia.com/wiki/Ai_Enma
As the series goes on, Ai does become slightly more expressive, and a tad less cold, serious, and silent. However, the difference is extremely minor. Interactions from her side are a little more varied, and less grim later on, especially toward her clients and victims. In some scenarios, Ai actually goes to the lengths of mocking clients a bit like her servants before sending them to Hell. She has also increased her attention and shown concern towards the more innocent clients and victims. An example of this would include the time when she reassured a lady who was requesting her to have Ren, one of Ai's companions, watch over her daughter after she willingly ended her life so that her daughter didn't have to be sent to Hell.
It is later implied by Wanyuudou that Ai still has her feelings, but just chooses not to express them much. It is revealed later on that she had been ordered to close off her emotions by the Master of Hell. However, in rare, but possible, instances, Ai has defied that order and used her emotions to guide her actions, as opposed to only following the duties given to her. The first of such series of occurrences is near the end of the first season, when she enhances through her actions the extent to which Sentarou Shibata's actions had hurt her. In trying to take revenge on Sentarou's living descendants - Tsugumi Shibata and Hajime Shibata, Ai's true hatred comes forth. She urges Tsugumi in many forms to make her send her father, Hajime, to Hell, although her attempts were deemed unsuccessful. She also burns down the temple which Sentarou had built while shedding tears, which is a sign of bearing strong emotions, although it is unclear what Ai's motives behind her performance may have been. One such time in which Ai is noted to be able to have feelings, but not express or act on them, is when Hone Onna mentioned that when Ai was being forced to send an innocent person to hell on a certain day due to her duties, she was silently screaming in her heart for having to do it.
