Board Thread:General Discussion/@comment-28702103-20160609173503/@comment-27701762-20160609192854

So this is working backwards to some extent: you're identifying your conclusion and then picking evidence that fits, so long as your conclusion holds true. That Mettaton's defense drops in his EX form is (canonically) a factor of the different bodies, rather than that Mettaton refused in one case to be hurt and at another point wanted to be hurt. If Mettaton specifically wanted ​to be vulnerable, then there should be some indication of this beyond the mere fact that the EX form ​is ​vulnerable. But the best indication we have is how Mettaton transforms, where the transformation is brought on by the protagonist flipping a switch on Mettaton's back. If Mettaton was specifically trying to be vulnerable, why not engage in this transformation of his own accord?

So you mention that the heart represents a human soul, but none of the souls we encounter is "pink," and while there is a soul trait that is similar to courage - bravery - that trait is aligned with the orange soul, not a pink soul.

Of course, you could respond to this by saying that since Mettaton is a human in hiding (or more appropriately, it would seem, a human soul in hiding), the pink soul was never captured, hence why we see it on Mettaton EX's belt buckle. And while the trait of the pink soul may not be "courage," it could be something else that we haven't seen.

But then the problem would arise in the battle. Whenever we see human souls, they retain their specific color in battle. Meanwhile, monster souls are always white in color. If Mettaton's soul is in fact human, then it should remain pink in the battle screen. But that is not the case: it is white, just like any normal monster soul. The only unique thing about his soul is that it is not upside down, but it is not clear what to make of this from the outset. (It should also be noted that for his NEO form in the Genocide route the soul is upside down, as you would expect.)

To sum up, there isn't really any evidence of other humans in the Underground. If any humans fell down that are not captured by the traditional Eight Humans, then they are likely dead and their souls were not trapped by Asgore, and they would have died long before Frisk falls into the Underground (since Toriel says that it has been a very long time since a human has fallen in).