(WARNING! This contains spoilers for Steven universe and Red vs Blue)
Recently, Pearl has shown very obsessive and self-destructive traits when it came to protecting Rose during the war. Even after the war, she held on to these feelings that practically shaped her into the gem we know today. I realized that this is somewhat similar to another character in fiction.
If you aren't familiar with the web series Red vs Blue, there is a character named Locus. Simply put, Locus is a cold hearted, quite, and somewhat sadistic mercenary who'd throw his own mother under the tracks if that was an order given to him by a superior. He seemingly displays a cynical/realist perspective on life, bearing the viewpoint that soldiers aren't meant to care for anyone or anything other then completing the objective to how they see fit.
But he wasn't always like this. We learn in a flashback, long before he became a mercenary, Locus was initially a more reasonable and compassionate soldier while serving under the army during a Great War. The squad he was part of cornered an enemy soldier and his captain orders to kill him. Locus suggests that they restrain the enemy rather than mindlessly kill him. His captain snaps at him and says "You're a soldier! In this war, you are nothing but a suit of armor and a gun! So when I give you an order you damn well follow it! Do I make myself clear?!?" Locus became who he is because his captain drilled in his head that he was JUST a soldier.
That got me thinking. Did something similar happen to Pearl? Perhaps Rose told her to protect her and she Pearl took it too far. Maybe Pearl figured that if Rose fell in battle, the whole rebellion would fall. So she took it upon herself to protect her at all costs. Whether this was brought on by Rose or Pearl herself is another story.
Another similarity between Pearl and Locus is that Locus tried to pass his ideology on Washington, a professional soldier who cares deeply for his friends, like Pearl did to Connie.
But a question remains. Why did these two not move on after their participation in their wars? I think it's common knowledge that war is a horrible and chaotic thing. All the killing, death, and violence can change a good person for the worst. Greg said it himself, there's no such thing as a good war. Soldiers constantly deal with psychological/mental problems even after the war is over. That's the reason Locus became a mercenary, he couldn't go to a normal life after what he did.
In conclusion: Pearl and Locus are psychologically damaged characters who took their roles in war too far. Locus taking orders no matter what, and Pearl protecting her leader no matter what.