The ooze is a sentient creature that seeks out hosts to learn more about the outside world. As it can't survive outside of it's cave without hosts, it will seek out folks to see and interact with the world through. As a host harbors the ooze however, they slowly transform and become something far more Eldritch than they were before. It'll give their host different abilities, to offset the often excessive physical changes they experience as the ooze grows in them and alters them more and more.