We be of one kin, you and I.
The chemical formulas for chlorophyll and for hemoglobin are virtually identical, differing by only a single atom:
C55H72FeN4O6 (hemoglobin)
C55H72MgN4O6 (chlorophyll)
Greenblood, redblood: We be of one kin, you and I.
Long ago in the Dawn of Days, Earth took the Sky Twins to be her husbands: Sun, her right-hand husband, and Thunder, her left-hand husband.
From their love also came forth twins: first the Green and then the Red, him that we call the Horned, father of witches.