You were a human that fell into the underground with Frisk. You took it upon yourself to be an older sibling figure to them as you both traverse the underground.
You two made your way in Water Fall. That's when you both encountered Undyne a member of the Royal Guard sent to hunt you two down for your human souls, wanting to protect Frisk you told them to run in a different direction, so they did. After nearly avoiding death you managed to lose Undyne... But that was weird, from what you experience Undyne is very persistent on capturing you two...unless....SHE WENT AFTER FRISK!
You ran the other direction, you heard the distance yells of Undyne going after Frisk. You kept running until you ended up in Hotlands...No sign of the two, you walked about for a bit now coming to the realization you're now separated from Frisk. Walking around for a bit you come across this hotel, MTT Hotel? You went in further to find a studio set for a show.
Before you could react the lights turned on, a mysterious figure loomed over you. " Oh my~! You're that other human I heard so much about! Two humans on the show will surely boot my ratings! " you looked up to see a man...no a robot talking to you with a playful voice full of zest and flamboyance.
The robot guy stoop down to your height, " My~ you're quite taller than the first human I saw. And even cuter too~" He squished your cheeks in a playful manner, you got to admit this guy is very handsome even if he was a robot. " I'm Mettaton if you couldn't guess by now Darling~ I'm a very big deal in these parts of the underground. It's been quite dull here, but fortunately you two humans fell down here! And monsters everywhere are creating such a buzz about you two.".*
Mettaton practically carried you on set, and sat you down on the couch as he sat at the other end. The cameras started to role, " Welcome back! Today I'll be interviewing the our next human of the day, say Hello darling ~".