You are enough, even as you look at all the things you can't do.

You are loved, even if you need to remind others to show it.

You will be cared for, even if you need to ask for it.

You don't need to change, even when you fail.

You deserve the best, even though you won't offer it to yourself.

 

Black in MtG is a self-centered and self-focused color.  The focus on "self" is actually more of a secondary point, but stands in contrast to White as I think that is the axis on which they are opposed (good for one vs. good of the group).  Black's aim is "power" and often we see that as not being virtuous because of all the associations with one person having too much power (and focusing only on themselves).  It's easier to see the problems with "too much" of Black (corruption, amorality) vs the problems with "too much" of White (disregard for individuals, dogmatism).

Correspondingly, it's also harder to pick out the positive traits associated with a self-focus.  Things like independence, self-sufficience, and yes, perhaps even self-care.  I think most people don't associate with Black as a color because of what I already mentioned, but funnily enough I think Slytherin house did a better job of making those ideals seem a little more approachable despite the house being super maligned.  I mean, that makes sense; Black spells are full of things like monsters and devils and decay whereas Slytherin might have a bunch of people of questionable character but at least they're human and there's a wide variety of them (some which you'd hope are not so one-dimensional).

Marco (from Animorphs) would probably be the one most aligned with Black.  It's not so much that he's self-centered, but more that he's willing to sacrifice other things in the interest of self -- "self" extending to the people he cares about.  It's a more personal definition of community and humanity rather than an abstract one.  He "sees the bright clear line" and I think that to me is a symbol of "ruthlessness" (I guess that trait is associated with Sultai, the wedge centered around Black).

Rachel would be Red for sure.  Ax, blue.  Which leaves White and Green for cassie, jake, and tobias.  Tobias makes more sense for green than Cassie, but I think Tobias feels more conflicted with this aspect than he draws strength from it.  Cassie I think would be White, and Jake...well, maybe he's just special.

Anyways..........