Hi! Remember the post you drew of Toriel with the soul of Justice, Grilby with the soul Integrity, Alphys with the soul Patience, and Sans with the soul of Perseverance? Now imagine Azgor with the soul of Bravery, Undyne with the soul of Kindness, and the Great Papyrus with the soul of Determination!
The MCs' soul traits are not paired based on their hosts' personalities, but rather what's most complementary to their hosts.
For example, Asgore wouldn't be paired with an MC who has the soul trait of Bravery, as the MC would not be afraid to be confrontational of Asgore's choices. Assuming MC arrives after Asgore collected six children souls, MC would be the soul that will worsen Asgore's guilt. With the way I see it, Asgore would need a soul who would be patient and understanding, encouraging him to a path of atonement. I imagine a Kindness soul would fit him better :D
This would mean that there'd be a switch up between Undyne and Asgore, in which Undyne gets an MC with a Bravery soul!! With Undyne's antics, I'd say it's a pretty good fit. Undyne and MC would be a comedic duo where they'd do batshit stunts that would give the people around them heart attacks. But of course, before that, Undyne has to get over her prejudice against humans, and I think MC being similar to her would be a good step towards that.
Lastly, yeah Papyrus couldn't get a more fitting partner lmao
