I have this headcanon where there was one time Petra walked in on Levi crying. Levi, Humanity’s Strongest Soldier, crying alone after losing about 75% of the scouts that went out with them on an expedition. Petra is shocked initially but it doesn’t stop her from coming over and cradling him. There’s no words spoken, no teasing or asking what’s wrong because they both know, and it’s then that they both bonded because of that moment. At this moment, only Petra’s seen him cry and she hasn’t told a soul and that’s why Levi has so much trust in her.