What ideas does Orwell bring out through the character of Napoleon?
Orwell brings out many ideas through the character of Napoleon. But arguably the most important idea he brings out is how he gains and maintains power.
First, Napoleon did not partake in any of Snowball's committees. Napoleon believed that there were more important matters. He had other plans - the education of the young. So, he took the puppies of Jessie and Bluebell and sequestered them. Later, when the puppies grew up, they became his guard dogs and his muscles. Here is what the text says:
Napoleon took them away from their mothers, saying that he would make himself responsible for their education. He took them up into a loft which could only be reached by a ladder from the harness-room, and there kept them in such seclusion that the rest of the farm soon forgot their existence.
Second, we also learn that Napoleon uses rhetoric to his advantage. In particular, he uses Squealer. Squealer is the silver-tongued pig who can weave words to make the greatest injustices sound just. So, even though Napoleon is not a good speaker, he knows that words are important and he uses Squealer to speak on his behalf.
Third, Orwell shows us that all power corrupts. The pigs initially, including Napoleon, probably had noble intentions for the revolution, but in the end, they became just as oppressive as Mr. Jones. In the end, Napoleon turned into "Mr. Jones." Pig became man and man became pig. Absolute power corrupts.