Actually, this is worth elaborating on.

As a character, Lexa had two major roles. First and foremost, she was the commander of the Grounders, who are currently in an uneasy alliance with the Sky People. Additionally, she was a love interest to the main character, Clarke.

Leading up to this last episode, Lexa’s political role had been putting her in danger. She was making controversial, unpopular decisions, which led to multiple attempts to dethrone or kill her. Lexa’s advisor, Titus, believed that these decisions were influenced by Clarke (which is true) and that their relationship would ultimately get Lexa killed.

A provocation from the Sky People put further strain on the alliance, and created political unrest as Lexa refused to retaliate. Clarke, realising that the Grounder capital was not a safe place for her, went to say goodbye to Lexa but instead they had sex (which sounds silly but it was actually super touching). Unfortunately, Lexa’s decision was the straw that broke Titus’s back, so he confronted Clarke when she came back to her room and he tried to shoot her. Lexa was accidentally hit when she heard the gunfire and ran into the room.

And like, I can see what they were going for. “Titus’s protectiveness of Lexa ultimately leads to her demise.”  The problem is that in Titus’s view, Lexa’s political role was being compromised by Clarke — which, again, is understandable, but having the death scene directly follow Clarke and Lexa’s love scene leads to the unfortunate implication that it’s primarily the relationship that got her killed. And then there’s the old pattern of killing a lesbian character right when she finds some happiness after a life of hardships, which is not very nice.

All that being said, I do have to give credit where it’s due: Lexa’s death is not pointless. Beyond the political and emotional consequences, it also deepens the show’s mythology and allows two previously unconnected storylines to intersect in a beautiful way. The writers took an unfortunate circumstance (Lexa’s actress was going to be unavailable moving forward) and made it a crucial part of the narrative. I just really wish they had given more consideration to the implications of their execution.

My thoughts.

I do wanna add the excellent point by Kylie about the physical cause of death: a stray bullet of randomness is cheap and doesn't fit into the story they had built up.