John C Wright's "eschaton sequence": Count to a Trillion The Hermetic Millennia Judge of Ages Architect of Aeons The Vindication of Man (and one more to come) It's a combination of hard sci-fi and space opera, based around one essentially immortal character (and his rival, and his girl) carrying out a mission over tens of thousands of years. Mind-blowing scale and yet there's a romance to it.
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