Every time Will touched Nico, he saw a glimpse of the darkness and sadness Nico had to live with everyday. It scared him. He couldn't see how one person could hold so much in one body and still be functional.
Nico was a lot stronger than he was given credit for. Sure, he looked like death half the time and needed constant support after doing Underworld-y stuff, but the only reason he survived all the shadow traveling and battles was because of his strength. Nico was constantly fighting for something, even if he didn't admit it.
That's what kept him alive in Tartarus, Will realized. Nico was holding on to some sort of hope or longing. He never gave up. It could have been so easy to give up. But he didn't. It gave Will even more respect for Nico.
Nico only showed his dark emotions- maybe out of spite of something. But the main emotion that drove his darkness? Love. It must be, Will thought. He wouldn't have gotten this far without it. Every action, every move... he did it out of love. He rose armies of the dead to protect his friends. He walked through Tartarus alone to help Annabeth and Percy and let them know what they were going to be up against. He only spoke good things about his friends when he encountered Bob, the Titan. Even something so subtle saved his friend's lives.
Sure, Nico was dark. He could be downright terrifying. But inside, he was full of love. Will was determined to show Nico that it was okay to show some of that love in other ways besides summoning ghosts and skeletal armies.
Will wasn't naive. He could see when Nico shuddered under his touch and his walls started coming down. Will wanted to push him out of his comfort zone just enough to pull some emotion out of him. Deep down, Will craved something from Nico. He was willing to wait until he was comfortable, of course, but he couldn't wait forever.
He'd spent several years at Camp watching Nico from the background. Every time Nico popped back into Camp Half-Blood, Will's heart fluttered. But back then, Nico was way too bitter. Talking to him was a no-go most of the time. Until the fight with Gaea, Will wasn't even sure Nico knew his name.
So holding hands with the dork was the best thing that had happened to Will in a long, long, long time. And he desperately wanted to hold onto Nico's trust forever.
On a medical standpoint, holding his hand willingly showed that Nico was getting emotionally stronger. To Nico, it might feel like he was getting weaker, or that he was letting his guard down. Will squeezed his hand tighter. He couldn't let him think that. No, Will cared for him. When Nico felt hopeless and alone, Will was going to be there for him.
Will started humming. Lightly swinging their hands, he sang:
"You are my sunshine, my only sunshine."
He waited for Nico to chime along. Of course, the kid was silent. Will nudged his shoulder. "Come on, Death Boy," he teased. "You know the words."
"I'm not singing."
"Why not?"
"Seriously? That song should be the Apollo cabin's anthem."
Will scoffed. "If you're gonna date an Apollo kid, you should at least show some respect to our song."
Nico growled. "No. And I'm not dating you. We're just walking on the beach. At night. Alone." He focused his gaze on the sand below them, a small blush spreading to his ears.
Will ignored him, even though he was cute. Like, really cute. "Pretty please?"
"No."
"It'll make you feel better."
"If by that you mean 'throw up', I agree."
Will stopped and crossed his arms. "Sing. Doctor's orders."
