There was something so undeniably real to this, something unbelievably awesome about having someone that you can confide almost anything in. Nino was simply the best in so many ways.
Adrien loved being able to just hang out and goof off and yet the next moment, talk endlessly about Ladybug without Nino judging him past a playful shove and an eyeroll. "She's a superhero, bro." And yet, none of that was meant to dissuade him.
Nino didn't seem to mind listening too much over the little kinds of things like Adrien could talk over everything but his secret identity with his best bud, and Nino wouldn't really judge him, just kind of encourage him along life.
Adrien often felt like he didn't deserve Nino, when he got Akumatized over something completely selfless for Adrien's sake no less, or any of the other sacrifices that Nino did for Adrien. It wasn't in a self hating way that Adrien wondered how he was this lucky to make a friend like Nino, just in a surprised, kind of grateful way.
Nino was the force that pushed Adrien towards new experiences and a deeper set of understanding; Nino was Adrien's first friend that he made while starting up school and was always willing to take a moment to reevaluate how Adrien sees the world to understand him better.
Nino was the person that could keep him grounded with just a few words and was like a brother in his own way to Adrien; someone that he felt like would always be there, supporting him, teasing him back and forth whenever they felt like it, and through both the good times and the hard times. Nino's a steady rock, and Adrien loves that quality in his best friend, loves how it keeps him going strong when trials push him.
Nino was everything that Adrien figured that a friend should be, just hopefully he returned the favor wholeheartedly and was the kind of friend that Nino was grateful to have.