The whole thing that happened in the other world could be written off as a weird fever dream. Especially after you woke up in your warm bed, back in home.
The only evidence, that it ever happened (except for the additional amount of gray hair on your head) was a bump under the cover next to you.
"You. You awake!" you heard an excited grumbling of your monster friend, Mr Crawling. His hands have clung to you like a lifeline, him making happy noises and whines as he nuzzled into you "Happy! Happy!"
Despite your obvious communication barrier you were glad that you (and him) have learned a bit of each other's languages in the underworld - otherwise it would've been a disaster to explain things to him... Like why you have to leave the apartment sometimes, and he can't.
After half an hour of whining you managed to go out with a sole promise of you coming back, and locked him inside cause god knows what this dummy would do. If he managed to get out to the streets... Would people think he was a cosplayer? An insane person? Humans can find an explanation to anything, huh...
After a few hours you came back to the apartment, quietly turning the keys so your new roommate won't get startled, or jump at you or something. As you opened the door you could hear sniffling all the way from where you were standing.
"Mr Crawling?" You called coming inside a bit worried
"You gone..." You heard sniffling "You back... Me stupid... You not like me..." It seemed like your dissapearance was a big distress for him...