i think the reason Genos is so important to Saitama is because city Z was emptying. people were leaving and saitama stayed. and when i think about how that feels it hurts. it feels so lonley watching everyone you know leave. and then Genos came. and he didnt leave. he got closer. he wanted to learn from him, saitma who doesnt know much. people left and didnt think much about staying for saitama even though he was determined to keep his city safe. but Genos was always thinking about him. he paid rent even though he knew Saitama was squatting, he helped with chores, he cooked his meals and even got features installed to help with this. in the episode when he gets amnesia he brings Saitama “game meat” (they eat monsters anyway so they didnt care) as an apolgy for how he acted even though wha happened was saitamas fault. Genos took the blame for it. he buys boxes of crabs for him probably with his own money. when he fails at getting to a sale on time he buys something better for him (again probably with his own money). Genos could move into the hero association building or use his S-Class money to buy saitama a better place. but he doesnt. he chose his sensei’s way of life and he doesnt push at him. he knows he’s self consious about his hair so he’s offered implants and advice. he does his best so saitama can enjoy his life. Genos is also seen repairing himself because his doctor pulled an allnighter trying to upgrade him. Saitama sees all these kind and considerate things Genos does for him. Genos doesnt see himself as human, hes easy to give up because he thinks he’s weak, but we constantly see Saitama try to tell him how good he is. and we see Genos finally understand how much Saitama cares for him when he touches his core.
its an indirect way of telling him he has a big heart. Genos is known to be serious, but after this and the fight with Garou Genos smiles more. Saitama showed him just how special he is. during the Saitama VS Garou fight Saitama holds Genos’s core the whole time. he was at his strongest in that moment and he couldve accidentally crushed it, but he didnt. he beat the shit out of Garou with the strength of a god, but he was gentle with Genos’s core, he protected it and kept it safe. he never let go of it. and when the timey whimey shit happened he gave it to Genos and Genos saw everything. all the memories from the core and what his sensei did for him.
