Okay so I have this firm belief that when Gaster created the skelebros, he did it separately. Sans was a test run at first, which would make sense why he has such a low defense level and attack level, yet his magic is outstanding. But Papyrus has a higher defense and attack level, yet he doesn't have such an amazing. I feel like Sans was meant as a helping hand in the lab but Papyrus was meant as protection for Sans.

Thing is, Gaster wasn't sure how they two would react to each other since he made Sans a couple years before Papyrus. Sans didn't know how to act with another kid, so he kept them separate and when they both seemed capable of living with each other, he had them meet.

And when Sans and Papyrus met, Sans couldn't say Papyrus, so he said Papy instead.

Now, I put that into the BindTale AU

Aaaaaannnd this happened

LONG STORY SHORT

This is how the nickname Oby came to be

MimiSnickersDoodles MINS IS TRYING SO HARD

*time skip*