My girlfriend just asked me to explain Halo lore to her. Need to invent a time machine so I can go back and explain to twelve year old me that dreams can come true.

Currently thinking about how in Halo 2, Johnson and Stacker were both survivors of The Flood outbreak on Alpha Halo, and they were both on the front lines fighting through them to recover the Index on Delta Halo. Was there a moment where the two locked eyes and realized what they were about to go through again? Where the trauma and horror of what they saw on the first Halo pushed at the edges of their minds, and they had to fight it down lest it take them? Knowing better than anyone the nature of the parasite, how terrifying it is that it's here?