What made Kanaya and Porrim turn into rainbow drinkers? None of the other characters do this, and while I’ve read that jade bloods turn into rainbow drinkers when they die, I feel as though it was a head canon instead of actual fact.

Rainbowdrinkerism is part of Jadeblood Biology, likely to aid them seeing in the Brooding Caverns and maybe feed off of something less conventional so they don’t have to move away too much? Shrug. Whether it ONLY happens when they ‘die’ or not, however, is to be seen. Kanaya’s regeneration actually ties in well to her being a Sylph, and Porrim is a Maid as well, so they could have that as a common thread for their Rainbowdrinkerism.