Tear Jerker / Mega Man ZX

• At the very beginning of the first game where after fighting a possessed Giro, he sacrifices himself to allow Model Z to lend you its power in order to survive. And in the implied backstory, Ciel is murdered by Serpent (who was supposedly her ally) during an expedition to find the Biometals.
• Towards the end game of Advent, Prometheus and Pandora get their revenge on Albert - only to have their energy drained by the real Albert and Model W. Even after everything they'd done, they were left to die at the bottom of the ocean in an exploding base. Probably one of the most depressing fates in the franchise for such memorable characters.
  • Extra material and drama CDs also highlight that at one point, Pandora and Prometheus were normal Reploid siblings. But Albert, being Albert, had specifically allotted them for his Game of Destiny - and then tortured them through confinement and conflict while forcibly and permanently merging them with their Biometals, and then hounding them with a limited life span to force them to do his dirty work to keep themselves from dying for hundreds of years. At one point or another, they just simply snapped, decided the whole world could burn for all they care, and started playing quite the Long Game for their shot at revenge. And then died not even a minute after thinking they exacted it in a massive "Shaggy Dog" Story, because Albert had expected this and exploited it for all their despair to feed to Model W.
    Model A: I didn't think this was how the game would end...
    Prometheus: [bitter laughter] What are you talking about? It's not over yet! We're still here! The garbage left behind by that scum!
    Pandora: We can't get our old bodies back... we can't change our destiny... so we'll hasten the destiny of destruction...
    Prometheus: We will destroy all that Albert made! That is our revenge! So let's have some fun, why don't we?! And go out with a BANG!
• When looking at the ZX series's position in the franchise as a whole, you realize something: Dr. Light's dream of humans and robots living in harmony as near equals has finally come true. And all it took was over 500 years, at least 2 near-extinction events, and three different inter-species wars. And while human/reploid quality of life is easily the best it's been in centuries, you can still see the effects of the wars in the landscape at times. And to top that off, there are still nutjobs out there trying to genocide everything, who arguably wouldn't have the means if Light hadn't gotten the ball rolling with his robotics.