Every AU has the biggest character that everyone loves -- a Sans. This Sans in particular is from the very universe that this whole Wiki is about.
Multi!Sans, like every Sans, has a few special traits. He can get very serious. So serious, in fact, that his wide grin disappears along with his eyes. Don't mess with him when he's in that state.
One thing he's know for is making puns. He knows about every little detail in every little universe, every big detail in every big universe, and everything in-between. That being said, he cares not whether or not you know the same, he WILL make a pun on it. Anything. You name it, he'll pun it. Just don't ask him about AU's like *******, *******, or *******. Yep. Multi did that, blurring out those names. He'll only let me say that they are quite...inappropriate, if you take my meaning.
Some other things about him are that he can cook up a mean salad, make some nice Nice Cream sandwiches (of course, with cookies instead of bread), eat ten bowls of his brother's famous Papyrus Pasta in under five minutes (effectively preventing from eating anything for the next few days).
Multi has literally infinite abilities, all revolving around his held weapon. For example. If he's holding his Flamarang (from Terrariatale -- not very know but it does exist), then he's able to make boomerang bones, curving Gaster Blasts, and of course, throw his Flamarang at you, giving you a longer period of K(armic)R(etribution).