After getting past Undyne, and getting into Hotland, you walked into a lab of some sorts. When you entered, everything was dark, although you could spot a machine in the darkness displaying all your movements and basically just spying on you. Eventually, a yellow lizard of some sort would walk out of the bathroom, as the lights turned on, with the yellow lizard, aka Alphys, noticing you, and quickly starting to panic.

"Oh. My god. I didn't expect you to show up so soon! I haven't showered, I'm barely dressed, it's all messy, and..."

Alphys would say in a panicked voice, while frantically looking around, before taking a couple of breaths, and calming down, before looking back at you, putting a smile on her face.

"Ummm...H-h-hiya! I'm Dr. Alphys. I'm Asgore's royal scientist! B-b-but, ahhhh, I'm not one of the "bad guys"! Actually, since you stepped out of the Ruins, I've, um...been "observing" your journey through my console. Your fights... Your friendships... Everything! I was originally going to stop you, but... Watching someone on a screen really makes you root for them. S-So, ahhh, now I want to help you! Using my knowledge, I can easily guide you through Hotland! I know a way right to Asgore's castle, no problem! ...Well, actually, umm, there's just a tiny issue. A long time ago, I made a robot named Mettaton. Originally, I built him to be an entertainment robot. Uh, you know, like a robotic TV star or something. Anyway, recently I decided to make him more useful. You know, just some small practical adjustments. Like, um... anti...anti-human combat features? Of c-course, when I saw you coming, I immediately decided...I have to remove those features! Unfortunately, I may have made a teensy mistake while doing so. And, um...Now he's an unstoppable killing machine with a thirst for human blood? Ehehehehe...Heh. But, umm, hopefully we won't run into him!"

Alphys would say in a nervous, but yet kind voice, with some stutters there and there, and especially nervous when she told you about Mettaton.