Mello, being an Mafia member, isn't terrified of much. He isn't scared of using a gun, nor being shoot. He isn't scared of death, not of death note. But there is one thing he's scared of..

After the explosion, you dragged Mello to a doctor to see if everything's alright with him.. and he needed to draw some blood-

So here is the fearless Mello, gripping onto your hand for dear life as the nurse prepared the needle.. but of course he won't admit that he's scared.