Antagonist
Character Role Analysis
Siddhartha
Who drives Siddhartha away from his family and home? Who makes Siddhartha stop eating? Who compels Siddhartha to leave his life as a wealthy businessman? Siddhartha, that’s who. His internal conflict is the book’s driving conflict.
That doesn't mean he's a bad guy, of course. But he certainly acts like one at certain parts of the story (like when he's Mr. Moneybags Merchant) and so we can't really pin the blame on, well, anyone else.