1. Something good to happen to those who don't use parasites... but they have no idea what good thing should happen or how to explain it in game, or
There are a number of ideas. I liked the BG1 model - you get something by trying to avoid becoming an evil monster. What that might be?
1. You are resisting power so: Resistance against psychic attacks? Increased wisdom saves?
2. Or, since these are tainted by the Netherese magic: any number of magic abilities. Something that duplicates spells in the game or some new ones.
3. Or, since the protection comes from Orpheus and he's a monk - so abilities that duplicate or enhance monk skills?
Explaining in the game? We have something with the Jaheria tadpole - they vibrate near each other.
Explaining it? How about the powers develop when we crush the tadpoles we find?
". . . your tadpole sends out waves of psychic vibrations. Its vibrations come to match those of the tadpole in your hand. It feels . . . sympathy? empathy? Both tadpoles vibrate at the same frequency and yours wants commune, to join, to become
one with the other tadpole. It wants to share and absorb this tadpole memories and to help you evolve. **crush tadpole** Your tadpole spasms, it feels so much pain - it's been injured and its presence somehow feels smaller in your mind. And you feel . . . stronger, better, freer"
