Here a list of new stuff I noticed in the Megilah this year that may be able to help you give a nice, good, drunken Dvar Torah at your Purim Seudah tomorrow. These are preliminary thoughts for development.
First, I noticed that, indeed, it was entirely Mordechai’s fault for endangering the entire Jewish people by exposing himself to Haman as a Jew. When Esther is kidnapped into the palace in a sadistic beauty pageant by a tyrant who wants a new plaything, Mordechai tells her not to tell anyone her nation or her heritage. את עמה ואת מולדתה are the words. כי מרדכי צוה עליה אשר לא תגיד. Mordechai commanded her not to say anything.
Why? What did he fear? Judging by Mordechai’s sitting at the gate, saving of the king, and respect for regulations (not going to the gate when he’s dressed in sackcloth), he was a political animal. So he probably didn’t want Esther to ruin her chances of coming out of this at least alive. If Achashverosh killed Vashti, who knows what he would do with all the women he didn’t want. If she said she was Jewish, Achashverosh might have killed her.
Second, why, when pestered by the people at the gate as to why he does not bow to Haman, does Mordechai not follow his own advice and shut up about his nation and heritage? כי הגיד להם אשר הוא יהודי. Same words as he uses in telling Esther not to tell anyone. But he tells. Reluctantly, after they ask him again and again, but he breaks. After that, they tell Haman, who decides to go after everyone.
If either Esther had told the king at any point after she was chosen that she was Jewish, or Mordechai had not told anyone that he was, Haman would not have been able to go after the Jews as he did. If word came out that Esther was Jewish, Haman would never have been able to go after us. If Mordechai had kept his mouth shut, he would never have wanted to go after us in the first place.
But because Mordechai tells Esther not to say anything, but he himself doesn’t follow the same prudent course, Mordechai is responsible for this whole thing, and that’s why he rips his clothes. He reverses when he tells Esther to reveal herself at whatever cost.
Amalek vs Agagi, Israel vs Jew
The Torah reading for Purim starts ויבא עמלק ויילחם עם ישראל ברפידים. Amalek vs Israel. Full nation versus full nation. But Haman is never referred to as an Amalakite. He is referred to as an Agagi. Agag is the king of Amalek, just like Yehuda is the king of Israel. So the royal stock of the Jews, represented by Mordechai both as a Benjaminite (Saul) and a Jew (Yehuda) is fighting the royal stock of Amalek, Haman. Two shards fighting one last round, one never to recover (there is no more Amalek genetic line) one to return.
Haman has Esav Qualities
Maharal points out the language of ויבז with both Esav and Haman. ויבז עשו את הבכורה, vs ויבז בעיניו לשלוח יד במרדכי לבדו. Same personality, same language. Further, Esav in meeting with Ya’akov who offers him gifts says יש לי רב אחי, יהי לך אשר לך. I have much my brother, keep what you have. Ya’akov responds with כי יש לי כל, I have everything, please take my gift. Chazal make a big deal about the רב versus כל, that someone who has רב always wants more, and someone who has כל is satisfied.
Haman has the same language. He tells his family, probably while drunk because he seems to be recounting his entire life story to his family who no doubt know it already, about his כבוד עשרו ורב בניו, his great riches and many sons. Not כל בניו, all his sons, but his many sons, same language as Esav.