Tris deals with important issues about identity and figuring out what it means to be selfless, courageous, smart, and kind as she makes decisions she thinks will help others.
Characters die from execution-style murders, committing suicide under mind control, being tortured/forced to do something dangerous, and from being in the wrong place at the wrong time. Lots of weapons and arrests and tank-like vehicles. Some blood, and a pervasive sense of peril/danger.
Tris and Four embrace and kiss several times. In one scene, kissing turns into more, and she takes off her top and then his shirt. The scene fades to black, but the next shot is of them in bed, bare shouldered under the sheets. It's implied they had sex and slept in the same bed.
One quickly uttered "f--k," plus a couple of uses of "bitch," "s--t," and "a--hole." Other insults include "stiff," "coward," "psychopath," "loser," and "stupid."