I once heard this beautiful vort, I think it was from Rav Pincus:
When the Jews ate at the seudah of Achashveirosh, the malachim went to Hashem and said, “Look at this terrible thing they’re doing! They should be destroyed!” And they were takah right, to the extent that Hashem let Haman write his decree. But then Hashem said back to the malachim, “Wait! I don’t care how terrible of a thing they’ve done, they’re my children! I can’t destroy them!” and he reversed Haman’s decree.
On Yom Kippurim we ask Hashem to disregard all the terrible things we’ve done and to remember that we are his children, just like he did on Purim.