Mass Effect 3.
The inevitability of the Reapers' erasure of sentient life sinks into Shepard, as he or she realizes that the term "human" no longer applies to him or her. The protagonist has been touched by an Asari's mind, that triggering fundamental shifts in neurochemistry in the average human brain, while the suspected proofs of slow-burning indoctrination also point to Shepard no longer being able to reason while remaining entirely free of Reaper influence. Couple this with the fact that the character's been extensively patched up by the Illusive Man's med team, and you're left with someone who's little more than a shell clinging onto bits and pieces of human ideals.
The Catalyst's words sink in, and the protagonist realizes he has no other choice but to speed the process along. All of Humanity and of the Council races will live on throughout the great singularity that the final moments of assimilation will bring about, later to be nothing else but spare mnemonic and organic data for Soverign.
For an instant in real time but an eternity in terms of Reaper computation cycles, all that is and has ever been will live on. All will be understood, all will end. There will finally be peace. The Reapers are our salvation from ourselves, and submitting to their rule won't so much extinguish the beauty of the Universe's current life forms, so much as all the pain and suffering they've had to endure.
Shepard doesn't see this as submission or capitulation. He sees it as the justified end of a long and painful crucible. The Catalyst's axiom resonates in his mind as he interfaces with it mind, body and soul.
The created always rebel against their creators - but not this time. This time, the cycle ends. Shepard's logic melds with the Catalyst's own points of view, and it resolves to "park" Reapers throughout former Citadel space instead of retreating back past the Perseus Veil. If one of the former inhabited worlds so much as develops the barest whisper of sentience throughout another evolutionary chain, it'll be burned to ash within moments.