You can find a comprehensive season overview and synopsis that breaks down the relationship between David Budd and Julia Montague.
If you are writing your own paper, these are the most frequently analyzed themes in the series:
The show is noted for its realistic portrayal of David Budd’s struggle with PTSD. Unlike traditional "superhero" tropes, Richard Madden’s performance highlights emotional vulnerability and the "scars" of war.
Some researchers have analyzed the character of Nadia Shanaa to discuss how the show attempts to subvert—but sometimes reinforces—stereotypes regarding Muslim women and terrorism.
This paper uses the lens of "post-militariness" to examine how the show portrays contemporary war veterans.