I'm thinking of the contrasts between Nico's and Will's griefs.
When Bianca died, Nico was all alone. He learnt her death and ran away. He probably shadow traveled to an unknown place, he spent an unknown amount time all alone (and months before he got to talk to anyone else than Minos). He was alone. He had nothing. He probably spent weeks, months, spiraling over how sad he is and how much he misses her and he hates Percy and replaying their last interaction in his head, drowning himself in his own grief.
Will, on the other hand, has always been busy. He was needed. After the Labyrinth battle, and especially during/after the Manhattan battle, he was desperately needed. As soon as the bridge collapsed (on Yew), 13 years old Will was grabbed to take care of Annabeth. And there was so much other campers who needed the help of the only Apollo kid/doctor remaining. By the time he had the time to start grieving his siblings, his family, war was over and the others were already celebrating.
Idk what's more messed up. A kid who has spent so long all alone crying his sister over and over. Or a kid who didn't have the opportunity to cry his brothers.