Bigson and Seresh tried to kill the king, Achashveirosh. Actually, some bring down that to keep the authorities off track, they were going to kill Esther too, and make it appear as if there had been a domestic dispute that resulted in a murder/suicide, with Esther presumably having died by her own hand.
Later on, when the king couldn’t sleep and had his records read back to him, the Megillah says “Bigsona V’Seresh” it calls Bigson “Bigsona,” with an extra aleph at the end. Why? The mefarshim answer that in order to lessen the greatness of debt owed to Mordechai, when the incident was recorded in the record books, it was written as if Mordechai helped capture only one of the conspirators, either Bigsan or Seresh, and the other was caught as a result of detective work. Thus originally it was written “Bigsan oh Seresh” meaning one or the other, and Hashem separated the word “oh” (aleph vav) and placed one letter on each name to read Bigsana vaSeresh. That is why it says “they found written” – it wasn’t what they had initially written. Instead, Achashveirosh’s advisors found that the separated letters now read that Mordechai helped capture both Bigsan and Seresh.
Thus we see that we can learn something from each and every letter in the Megila.
