From this ask meme.

“Who do they see as their best friend? Their worst enemy?”

My initial thought for this was “his brother”, but then I realised I don’t actually know much about Swapfell Sans (Black? I don’t even know what most people call him.)

So, Cash’s brother aside, I feel like he’d get on really well with Blue. (I seem to have a thing for shipping Blue with any Fell version of Papyrus). Although really, I think these two would be better platonically than romantically. I think Cash would find blue’s boundless energy and kindness very entertaining, and perhaps even endearing once they grew closer.

As for his worst enemy, I’m going to have to say Razz. (But I mean, which of the skellies don’t initially despise the short tempered little shit?) Skeletons aside though, Cash would have a deep mistrust of Alphys (assuming Alphys is the Royal Guard captain in this universe…? Again, I really don’t know enough about it to properly answer this question. I think I actually know more about Kit’s Twistfell AU, if anything.)

I think it’s a shame that Swapfell (… Fellswap?)–the purple one–often gets overlooked when it comes to fanfiction. It gets a bit difficult juggling so many AUs, and it’s normally a bit less confusing to stick with just Slim and Razz. I really like Cash though, so I’d definitely consider throwing him into some of my stuff later on!