They don't like to touch other people.
Shizuka doesn't like to touch people; living as he is has taught him the importance of purity.
When Shizuka touches him, the archer is relieved. Before Watanuki his life was dull and gray, with him there everything is sharp and clear . His obstinacy is fascinatingly frustrating and he is the only person who can make the stoic boy anxious.
Himawari doesn't like to touch people; she never knows when her curse will affect them.
When Himawari touches him, the cursed girl feels anxious. She fears for his very life every time she's near him but she can't help but want him there. She laughs when he is with her, he is the only one who lets her know she is sane.
Yuuko doesn't like to touch people; you never know what can happen with what is left behind.
When Yuuko touches him, the witch feels sane. She deals with the supernatural and insane daily, and his touch lets her know he is still there. With so much on her mind, it is good to know that something can still make her feel relieved.
They know the world is still real because he touches their lives.
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A/N: School is done so hopefully I'll have more time to write, and I do believe that I've been repeating the same basic concepts too many times. Thank you to all who commented for the encouragement. Requests? Reviews?
+Andy