spontaneous Monster Kid (from Deltarune) headcanon:
people have commented on the apparent cross shape they're wearing as a pendant, though seeing as how the "cross" is merely five pixels arrayed like a Swiss cross, it's conceivable that the pendant isn't actually a cross at all, but some more complex shape that looks like a cross at low resolution. maybe it's a Sun with four rays, or a schematic diagram of a tetrode with four conductors sticking out of it, or some other thing that looks like a cross if you squint. but I'm going to stick with the idea that it's a cross. I like that idea, but a Swiss-style cross is also another thing: it's a plus symbol.
therefore I choose to speculate that Monster Kid really has joined some sort of cult, which is perhaps why they come across like a bit of a judgmental asshole now (am I wrong?), but it is NOT Christianity, but instead something whose symbol and central motif is the addition symbol. it's like...believing in the Angel isn't enough, in this cult that I've just invented. you have to add something else, an improvement. It's not enough to be plain old MK anymore! meet MK Plus.
~Chara