Dealer's choice, go with whatever's more fun. If you think it'd make it too easy on him, the eye can be mysteriously blind. If you're still able to work with it and enjoy yourself, sure, let that eye shine bright like a diamond.

eta: but let's raise the stakes a little.

If you choose to have Stephen see the Motherless when he uses the third eye, the Motherless can also see him at that time. They'll target.

Before you ask, yes, the Motherless might try to latch onto Blob.