asides from UTKS, i do belive that the Integrity and perseverance humans had a relationship before they died, like they were siblings or friends, why am i telling this? well..we don't know much about the previous humans i know but if you look closely, Integrity and perseverance are always close to eachother

in the pre-Asgore fight scene

in the full coffins' room screenshot

and even in the Omega Flowey fight, their sections are next to eachother

also if you think about it, dark blue and purple are pretty much close to eachother in color scaling

many people might say that is how the souls are ordered in the pre-Asgore fight scene and in the coffins' room, it might be, but the way kindness, bravery and justice are displayed in both the pre-Asgore fight scene and the coffins' room are different while Integrity and perseverance always seems to stay close to eachother

at the end of the day, this was a pretty short theory of mine but a wholesome detail that i wanted to point out :)