Yes, it seems to me that they have partial control, since the purple one could strangle the MC. But what intrigues me most would be the colour change in his name. When he talks to Natsumi and has the green text, is it the green (benevolent, caring) side of his personality overriding his logical thoughts ? Or is it the deity herself sort of "possessing" him and controlling him without him knowing.
Also thank you for your condolences. I will say it has left a mark on me, and stories like these only make me feel glad that the victims receive help, albeit fictional.