Anywho...
Out of all the many Undertale AUs out there, Zarla's Handplates is currently my favorite. It's deep, emotional and well-drawn, has great dialogue, and really makes the reader think about the different moral viewpoints the characters present. (Fair warning: If you're going to read it, prepare for pain, anger, and a potent urge to decapitate a fictional skeleton.)
It also has some goofy side comics, like the one where Gaster found a sexually explicit fanfiction Alphys had written, involving herself, him, and several other monsters.
This sparked a discussion about the logistics of Alphys dropping and possibly reattaching her tail, which resulted in me speculating about this interaction, which resulted in this picture.
Such a serious and poignant AU, and my first (but probably not last) fan art for it is a goofy one-panel about Alphys using a Finding Nemo reference while freaking out about Gaster (almost) touching her butt.
As a bonus for those of you who are familiar with this AU: Alphys is hiding in the same closet Gaster locked her in in this joke comic.
If you'd like to see art like this early, to get exclusive access to WIPs, and to support me as an artist, please check out my Patreon.