Answer:
A tragic character's reversal of fortune.
Step-by-step explanation:
"Antigone" by Sophocles revolves around the tragic story of the protagonist Antigone whose act of defying the king's order and burying her brother led to her death. The play delves into the themes of family over everything else, the loyalty of family, the need to preserve it, and the various power dynamics in the society.
The given speech by the messenger is from the scene after the deaths of many of the characters. The messenger reveals that Creon's son Haimon had also died leaving only Creon and Ismene alive. The messenger's way of putting his words, describing Creon as "once a man we all looked up to" reveals a change in that person, i.e. Creon. The use of "once" suggests that whatever that was is in the past and now, that person is changed or different.
So, the messenger's words reveal the reversal of fortune of the character of Creon, the tragic character.