What is Snape's biggest fear? That question has been on the minds of many readers since first introduced to the intimidating ex-Potions teacher. I myself have a couple ideas as to what a Boggart might reveal if confronted by Snape, these ideas being A) Harry dead or B) Being alone.
I have sufficient reason to believe that each of these ideas are reasonable in prediction.
Snape is a mysterious character in all respects and this quality is what makes it hard to determine many things about him. Harry dead would be a fear that would surprise many people and would also prove him to be the redemptive character he is. He would be afraid of Harry dying for many reasons, a couple of which are 1) Harry dying would leave the Wizarding world in almost certain destruction and 2) With Harry dead, Snape would lose the last remaining visual reminder of Lily (remember, Harry has Lily's eyes).
Being alone would also suffice as Snape's biggest fear because first of all, many people assume Snape to be one of the most powerful wizards out there. While this may be true, power doesn't negate normal human feelings, which is why something so ordinary being a powerful wizard's fear is rather clever. It shows that Snape truly is a human being. Besides that, I think that Lily's absence had a profoundly negative impact on Snape and he feels that she was "The One." Now that she's gone, he won't have another chance at love, therefore leaving him alone, exactly what he does not want to be.
Those are just what I'm thinking as of now. I honestly think that these are more ingenuitive fears because they evoke emotion on a deeper level and would suit the character better than something like a fear of light bulbs or snakes.
