Death is always near us, whether we want it or not. Death can't be avoided, no matter how much we run from it.
Nico di Angelo knows death like it's his best friend. He often helps younger demigods on their deathbeds. Then he takes care of the funerals. Some people think it's creepy, but he wouldn't trade it for anything. He liked giving them comfort in their last breaths. Sometimes he talks to them in the Underworld.
Nico di Angelo isn't afraid of death. He's just afraid that the ones death welcome are the ones he has close to his heart.
Will Solace is always surronded by death. He knows that his patients can slip away any minute. He knows that he himself can slip away any minute. He knows that he could take his own life by trying to save someone else's one day. But he liked when he managed to save them from death. Even if it made his boyfriend angry, because you can't avoid death forever.
Will Solace isn't afraid of death. He's just afraid that the ones he deeply cared about were the ones he wasn't able to save in time.
Death isn't something you should be afraid of. But losing loved one's to death should.