He could also be protective. Despite their differences, Draco might have some hidden feelings for Hermione. So, when he sees her scared, he might put aside their past enmity and try to comfort her or keep her safe from whatever is causing her fear. For instance, if there is a threat from another student or a magical creature, Draco could use his Slytherin cunning to protect her.
Another possibility is that Draco uses Hermione's fear to his advantage at first. He might try to manipulate the situation to get what he wants, like getting Hermione to do his homework or something similar. But as he sees the real distress in her eyes, he has a change of heart and decides to help her in a more sincere way.