"How can you do that?" Marco didn't understand a lot of what Nico could do. He wanted to learn about it all. This was a new facet, sure, but Marco didn't judge. he was curious, and maybe a little bit fascinated. it was part of Nico, and it intrigued him, but there was no fear or judgement. He trusted Nico, and had no doubt Nico would keep Marco safe if necessary.
"Seems like it would be difficult if you don't know what it is, or what's causing it."