Hawthorne was in charge of the Government of the Starship UK, put in charge under the Queen at the time. He was responsible for making the Smilers, a race of androids that were used to police the Starship UK, and turning the space station into a police state. He believed this was necessary for the continuation of the Starship.
Hawthorne was responsible for the continual torture of the Star Whale, which he controlled via painful technology that attacked its mind - believing that the creature would only aid if enslaved: as a form of twisted "democracy" Hawthorne arranged for a vote every now and then amongst citizens of "Forget" or "Protest".
If citizens voted "Forget" they would have their mind's erased so as to forget about the nature of Starship UK and if they voted "Protest" they would be fed to the Star Whale - unsurprisingly almost all citizens voted "Forget".
Hawthorne also had a similiar system in place for the ruling Queen, who could vote "Forget" or "Abdicate" - the latter would free the Star Whale but (in the mindset of everyone aboard) would doom the vessel in the process.
Upon learning the truth about the situation the Eleventh Doctor decided to render the Star Whale brain-dead in order to stop the creature's pain while also saving the humans on-board, though he was outraged at the way they had treated the alien.
However as the Doctor prepared to do what he felt was necessary his companion Amy Pond saw that the Star Whale, while aggressive towards adults, was still caring for children - she then convinced the Queen to press "Abdicate".
The Star Whale proceeded to carry the vessel and moved faster than before, not only willing to keep humanity safe but also performing its task more effectively as it was free from pain.
Hawthorne was geniunely surprised when he experienced this and presumably reformed - though it is unknown if he will have to face any form of retribution for his misdeeds (though they were more misguided than malicious).