This is a concept for a set of conjoined characters.

After a set of body modification experiments, they became attached to one another. Over time, feelings developed after the experiment was dismantled.
They like each other but are way too awkward about it, so they think the other isn't interested.
The back one is an introvert and hides behind the front one, while the front is the extrovert, and enjoys feeling the back one's skin contact on his back.
The back one always hugs the front one. The front one tries to make situations where he can understand the back one's feelings for him.

Only a close friend of theirs' understands the full situation, but he seems to like how funny the situation is, so he just watches on.

I do not have a name for these two, nor a color palette. But I like the idea of someone hugging their conjoined partner from the back constantly.