I wanted to touch on the transformation of Wikus in the film not from just a human to an alien but how he grew from being an unlogical, goofy person to a brave, convict who did whatever possible to get his life back from the shambles MNU and his father in law turned it into. In the beginning of the movie you see how Wikus is somewhat type B, as a reserved person who is afraid of confrontation. He knocked on the doors of the aliens to evict them but then stumbled and was taken aback from them once they answered the door. His voice and face were all evidence of these actions as you could easily tell he was scared.
As he started to realize his body was going to be tampered with and that MNU was inevitably not going to help him, he knew he had to act and fast. By escaping to District 9 and taking his life into his own hands, we see how he became ruthless and did anything to survive, much unlike how I believe the old Wikus would have reacted.
This reminds me of Spirited Away and how Chihiro had to grow up quickly in order to save her parents and herself. Wikus knew that in order to save his life, and get back together with his wife, he needed to do anything in his power to save the aliens and become human. District nine may be a sci fi flick but I see the underlying message as doing what you have to do to see your desired effects occur.