If she will refrain, why should her father's house perish?
Vilna Gaon: "Beis Avich" are your colleagues, like it says "Misrapeh vi'Mlachto Ach Hu l'Va'al Mashchis" (Mishlei 18:9). This is if he can save, and he does not save. Not only does he not get reward 1 - he is like one who kills. Beis Avich (others who could have saved) will perish, and all the more so you, the queen!
Nachal Eshkol (Chida): Esther comes from Sha'ul, who did not wipe out Amalek totally. She has a chance to fix this. If not, she and Beis Aviha (Sha'ul's descendants) will perish 2 .
Malbim: If she will be quiet, automatically she and her father's house 3 will perish. She will perish, for the reason for her grandeur will be Batel.
What is the Chidush that one who does not save, he does not get reward? (PF)
Do not say that also Mordechai is from Sha'ul, and he will survive. Even though Mordechai was "Ben Kish" (2:5), Ibn Ezra there says that he was not necessarily from Sha'ul. (PF)
Malbim did not explain why her father's house will perish. Perhaps he explains [unlike Ibn Ezra] that there was no one else from his father's house. Even if she was orphaned from birth (refer to 2:7:4:1), she could have had older siblings! Perhaps our verse teaches that she did not. Or, if she had mature sibling when her father died, they should have adopted her. If she had young siblings, Mordechai should have raised also them. (PF)
Why did he say "u'Mi Yode'a Im la'Es ka'Zos Higa'at"?
Rashi: Who knows if the king will desire you in the coming year, which is the time of killing? Now it is Nisan; the time of killing is in Adar in the coming year. Will you be in the grandeur that you are in now?
Malbim: Do not think that you will save the Jews later, when the king will call you to come. Perhaps Hashem prepared you only for this time, to save them today 1 . If you will wait, your time will pass, just like a winter house is not needed in summer, for there are other means to grow vegetation then.
Why did Mordechai agree that she enter only after three days? Since they will fast for her to succeed, it is as if she is already engaged in saving. Similarly - Hashem made Ma'ase Bereishis contingent on Yisrael accepting the Torah on Sivan 6 (Rashi Bereishis 1:31, from Midrash Agadah). R. Yosi holds that we delayed until the seventh (Shabbos 87a)! Since we delayed in order to accept it in greater Taharah, it is as if we already accepted it. (PF)
