Dear Noxporium: “How do you know you can trust an entity?”
The short answer: You don’t.
The long answer: You establish boundaries and enforce those boundaries. If the entity respects the boundaries you have set, then you’re good and you know how far to trust them. If the entity does not respect those boundaries then you have to evaluate the relationship between you and make a judgement call if to surrender your autonomy, renegotiate boundaries because of the circumstances, enforce the boundaries with prejudice, or call it quits entirely.
This holds true regardless if the entity is your family member, your roommate, your coworker, or your boss. It also holds true if the entity is incorporeal from the wee little fey that lives in the old mouse hole to a god that is insisting you leave all and follow them. If you have not already promised/oathed yourself in a binding contract then it is your choice if to create such a promise/oath and to what degree you are willing to be bound. I am very well aware that the chaos of life and living doesn’t always make for the cleanest of circumstances or the clearest of examinations. But one does what one can as well as one is able.
Emotions can make a clotted soup of even the clearest broth. If you find that your emotions are overriding other instincts (such as the instinct of self-preservation or the desire for clarification), ask a trusted third party to examine the situation and help you see what your emotions are trying to hide.
Ultimately, it is your choice what boundaries to place before the entity, and your choice how fierce to enforce them.
Be well. Be safe.