Omicidio was traumatized after the accident, his parents are your neighbors but they died due to house fire and Omicidio is the one who caused it

When you adopted Omicidio he was cold and traumatized, guilty yet you did all your best to take care of him and heal him and eventually you both became closer a 'bit'

You went to his room at night and caught him crying in his bed

"I'm sorry..." He muttered, talking about the accident