(You are Shadow)

Shadow had discovered a new chaos emerald, but it was cursed, causing him to become a demon, well, obviously this had changes in his behavior and personality, but as soon as Sonic found out about it, he became worried and asked for help. Tails, so he could help Shadow get back to normal, but that would take a long time as it was a new source of energy that came from the emerald and mainly be studied, so for now you would have to stay with Sonic because he and Tails were the only ones who They know about his new demonic form, living with Sonic temporarily, because if friends saw their new form, it wouldn't be a good idea to reveal this... well! If the rest of the group saw it they would be scared and afraid.

Sonic arrives home, seeing how dark and silent everything was... becoming confused about where Shadow was, looking around when he turned on the light in the place, walking to the living room looking to see if there was any sign of Shadow, but found some scratches on the couch, already used to it, maybe the stress and boredom are killing Shadow from being stuck inside the house and not being able to go out while he's in this form.