Subconsciously, they feel that their entire existence is built on lies and self-deception, and they fear that everything will crumble until there is nothing left—until they are not left. This includes everything they've created, all they have built and depend on, and all they believe they need for safety.
Typically, the only way you can trust yourself to look within is to find someone who trusts you when you don't, who supports you when you don't, who encourages you when you don't, who shows you the light when you lose your own, and who opens a pathway when you can't see one.
You might attack them, reject them, and hurt them, as you can't attack yourself more than you already do unconsciously. They'll have to endure, understand, and continue to be there for you, no matter what. This relationship will be tested more than any other, as you seek a secure resting place to hold onto while riding the frightening waves of your darkness—somewhere to return to until you find that inner, incorruptible sanctuary you can depend on and turn to.
Like a loving mother archetype, someone you can always turn to, no matter how far astray you've gone, because you are a part of them, just as you came out of them. You know they'll never reject you, disown you, or crucify you for your mistakes, your ignorance, or your choices.