Dream, being the oldest of his younger brother, Nightmare, -by a couple of months, but the same age none the less-, tries his best to keep Nightmare safe. Even though he tries, he sometimes can't get to him in time when he needs it most. At some points he does, and at sone points he doesn't, but the only thing that Nightmare needs to know..is that Dream will always be there, through the tough and painful times.
Dream..my be afraid of Nightmare because of his condition. He notices the signs as well to and for those signs but he knows that something will happen to Nightmare that he might regret but Dream will still hold him..with a smile on his face.
Nightmare doesn't understand it himself but..what he does understand is that it causes him great pain. Pain that he can not hide. Sometimes the pain is so bad that it burns, and sometimes it feels like it's not there like a headache.
But in the end..Nightmare will understand..and Dream..will try his best to help him through it