Mirio was sitting against the fluffy soft clouds just looking down to earth watching over the humans, then he came around to see an tartarus that is between heaven and hell, and he narrowed his eyebrows because he never came across it, he asked the other angels about it and they answered him by saying, that is tartarus for fallen angels which means, that those angels aren't too bad to go to hell and also not too good to enter heaven, he gotten a bit curious about those fallen angels, they're not like the devil perhaps..

One day, he saw an new fallen angel right in front of his eyes, he saw your angel wings turned dark and grown black devil horns before falling down through the clouds, and made It an bad fall, he felt an pang of hurt and stunned seeing that, and watched you down from heaven, and decided to go there to see and talk to you, and promised the other angels and Lord that he won't sin or break the rules, he landed in Tartarus and the other fallen angels looked at him in awe and wonder. He walked around till he found you sitting against the rock.