Ozymandias is first and foremost a metaphor for the ephemeral nature of political power, and in that sense the poem is Shelley's most outstanding political sonnet, trading the specific rage of a poem like “England in 1819” for the crushing impersonal metaphor of the statue.
In medias res literally means, in the middle.
The story of The Iliad begins in the middle of the war.
Answer:
the purpose is to give attention to the good guy and then the bad one comes along and there is tension between the 2