Ismene
Under the Aristotelian method of analysis, Ismene would be considered a character that is "like us." This is because she lacks the fiery, passionate spirit of characters such as Antigone and Creon. In the play's opening scene, for instance, she expresses her fear and concern for Antigone, but is largely passive and eventually bends to her sister's will, despite her personal feelings. On the other hand, when she appears for the second time (as Creon's captive) she displays a bit more backbone in her proclamations of loyalty to Antigone. However, despite this slight transformation, she is once again rebuffed by her sister's domineering personality and ceases her attempts to die with Antigone.
Ismene can also be considered a foil to Antigone. It is obvious that the two are meant to be looked at in comparison, as they are sisters. Hence, upon inspection, it is revealed that the two are almost complete polar opposites. As stated before, Antigone is passionate and fiery whereas Ismene is more calm and passive. In addition, Ismene shows much more concern for the physical and material environment of kings and worldly rules. Antigone, however, is primarily concerned with a higher calling dictated by the gods, and is prepared to defy Creon's authority in following this calling. Overall, the two characters represent a characteristically Greek character conflict: that between reason/logic and emotion/passion.
Teiresias
Teiresias, under Aristotle's character types, is a stock character. In the play, he is the archetypal blind prophet/harbinger of doom. The blind prophet, as many stock characters do, embodies a crucial contradiction: one who can see the future and yet cannot see the physical world around him. Also, Teiresias serves as the messenger of doom, also a stock character, one who is often possessed of supernatural powers and/or a connection to the divine; this aspect of Teiresias’ character also suggests that he could be viewed as a unique/unusual character (due to his gift of prophecy).
Teiresias also provides an interesting take on the classification of a raisonneur. He serves as the voice of the gods and conveys their displeasure with Creon's actions. Whether or not this is the voice of the author cannot be known, but Teiresias is essentially the voice of an outside observer (the Olympian gods). It is unlikely that he is the actual raisonneur of the play, but it is important to note that he IS the voice of beings that exist outside of the play's world.
Chorus
The chorus (which, for these purposes, can be considered a single character), like many other characters in the play, is very much like us. The members of this group, who represent the elders of the city of Thebes, respond to the inquiries and statements of the characters with characteristically "normal" responses. Also, like Ismene, the chorus essentially takes no effectual action in the entire plot. They comment on the actions of other characters, however, and speak their opinions, but, as stated, they are largely a passive entity.
It is very likely that the chorus serves as the raisonneur of the play. When they are interacting with characters such as Creon and the Messenger, they ask questions and express opinions. To go along with this, when the chorus is engaging in one of the typical choral odes between "scenes" they expound upon philosophical ideas and larger concepts within the plot (covered in Thought/Idea). These roles characterize this particular chorus as expressive, but still quite passive. This makes it seem very likely for the chorus to serve as the raisonneur.