[quote]Like where Humans came from. [/quote] precursors. they were a really advanced race of transsentient beings who basically seeded galaxies with life everywhere. they supposedly created forerunners and humans. of course, the forerunners managed to kill them off. [quote]What the flood is. [/quote] precursor dust. basically when the forerunners tried to kill them, some precursors turned themselves into regenerative "dust," so they could reform into their old shape later. this dust corrupted and the precursors became abominations. however this also gave the precursors their ultimate method of enacting revenge and shaping life in the galaxy as well, hence why we deal with flood now. [quote]Who created them and why. [/quote] ^^ [quote]Who are Prophets [/quote] another race in the milky way. you see them in halo 2. they were among the most technologically proficient of the races before the halo installation fired when the forerunners tried to kill the flood. after the firing of the rings they quickly became the leaders of the covenant [which will be detailed in depth in a novel later on this year]. [quote]and Precursors. [/quote] explained already [quote]And if the Halos killed absolutely everyone. [/quote] they didn't. special installations such as shield worlds, the arks, and even specialized parts of halo rings themselves were immune to the halo pulse and the forerunners kept species there. their plan was to reseed the galaxy with these species after firing the rings to kill the flood. [quote]Why do we even remember any of this. [/quote] ^^ [quote]Why are Forerunners and Humans fighting again?[/quote] not all forerunners are fighting humans now. just the didact and his extremist forerunners. if you'd like an explanation on that i could do it, but it'll be a whole new ballgame as it'll take you deep into one of the universe's most complex characters.