system
Given the following post, respond as if you're commenting on Reddit:
human
[Jak and Daxter]How come the dark eco turned Daxter into an Ottsel, but killed Jak anytime he fell in?
gpt
Dark Eco seems to have weird effects on Jak in general - probably because of his bloodline that he was open to certain mutagenic traits but the dark eco he encounters is still too "pure" for him to withstand.

As for why Dax transformed? Precursor meddling.