Arrow Lake this empty northern hemisphere

He's trying to get a rise out of her—and well, he's a bratty child in the moment, suffering as he is. It is not a good excuse for treating others so poorly but he doesn't care; he's hurting, so they should be too. His words hit her ears and she reacts as he wants her to, offended and raging. It is a surprise to Mesa that more people aren't raging for the loss of life upon the mountain; why was it that he was the only wolf able to identify and act upon his anger? How could everyone else let the death of Stigmata fade away so swiftly? He was, of course, oblivious to the internalized struggles of Diaspora. All he felt was his own ineptitude, his own aching wants, his own selfish need for a father that wasn't anything more than meat now.

The girl is yelling in his face again. She's protesting, trying to prove to him she's more than nothing, but it doesn't matter what she says; she is not his blood. She is not one of the children of Stigmata, and to Mesa that is everything. Her raging voice fills his ears in retaliation and yet Mesa scoffs. Your people? What people! You have nobody! It was Mesa who felt like he had nobody; he had effectively hidden from his siblings and avoided all interaction with his father's grave to date, and by hiding from the pain of it all he'd made it all worse for himself.

He flashed his teeth and warned her with a low note rumbling like gravel at the back of his throat, crowding nearer. 

Just because your mom calls you cool doesn't mean that you are! He berated her. You're not special, you're just some kid! Whether he was talking about Praimfaya or himself is unclear at this point, but really it could apply to them both. He was staring her down now, hoping she'll fight, hoping she'll take all that anger and do something because he felt like he couldn't breathe for all the pain he felt over his own family.