Everything they saw in the Sky Castle was preposterous; every memory Mathias triggered had to be false and yet held that distinct clarity of truth. The awful truth, then, the one that caused Luca to freeze up, lose himself, forget who he was and only remember what Asura had done (as though Asura had really 'done' anything – the true blame fell on their shoulders, Durandal and Inanna, betrayers).
Maybe that's why it was so difficult for him to accept it, to deal with it and to cope with it; they had just left him there while the entire thing came crashing down. Maybe there was nothing else they could have done, sure, and in the end it was the simplest fight-or-flight response: be buried alive together or be buried alive alone. It didn't make it better, more righteous, more correct; it only dug the guilt in deeper, clawing and scratching and gnawing at whatever it could get its hands on (at that moment, him). It was self-preservation in favor of sacrificing someone who had done nothing wrong, something sounding too similar to what had happened thenand therefore only bringing about bad taste and bad blood and bad feelings.
He didn't have the good sense right that moment to realize there was no real way to save Luca, and there was no way to keep that castle from crumbling into pieces and falling into the earth after so many thousands of years. To him, the only thing that mattered was that he had promised he would never let Luca die – he would protect him.
But they had left him without a second thought, and –
Then nothing. The castle had collapsed, the ruins landing just outside Sania, no one bothering to check them as though it were automatically a lost cause. Just accepting that Luca was stuck somewhere under all the rubble and debris, not thinking for a moment that maybe there was some semblance of hope that he wasn't dead yet, that he could be saved and Spada wouldn't have failed him again – three times, then, counting Hasta because god knows he did.
He did not ever collapse in on himself, even despite his constant failures, and the entirety of his stay in Sania was relatively normal barring the constant reminder to breathe, the crushing pressure on his lungs and his heart and his everything.
His only salvation was keeping his faith in Luca's resilience and resolve to live alive until finally, finally, the familiar silver-haired boy came hobbling into the village, worn and weary but alive.
Then he could breathe, shaky and steady at the same time, like the first breath after years in coma.