The fandom seems to think that Percy never treated Nico well, but after re-reading PJO and HoO, it's more often Nico who treated Percy badly (for no reason too).
Percy was never mean to Nico. In fact, he always wanted to protect him, especially after Bianca. The only time Percy was mean to him, was when Nico had literally lied to him and tricked Percy and gotten him captured by Hades. If you ask me, that's a pretty valid reason to be mean lol.
Also, Nico was wrong for being angry at Percy for Bianca's death. I know, he was only a 10 year old and he had to put his anger onto someone, which is why I still sympathize with him even though Percy didn't deserve that anger. And, Nico hating Percy because Percy didn't like him isn't valid....Percy wasn't even aware of Nico's sexual orientation, and Nico had never given Percy any indication that he had a crush on him. According to Percy, Nico hated him.
I really like Nico, but I think at this point the fandom has kind mixed up his character and forgotten alot of things that happened in the original PJO series. Percy was literally always trying to be a big brother to Nico, and I wish people would stop erasing that.