ok let me explain my line of thought.

SANS = yellow eye = yellow = FAME.

Sans is immensely famous, but he can't express love.

sure, he can say he loves something, even care for his brother or his ketchup.

but when did he ever express anything other than a **smile**?

his brother, Papyrus, knows Sans loves him, but it's just overshadowed by his jokes, which most of the times feel like it's just seperating the two, even if it isn't the case.

Sans, is Famous from his jokes, he's popular, but that fame is driving him away from the people that HE loves; Everything that seem to relate to Friend's deals.

he asked for fame, and lost his love.

PAPYRUS = **LOVE**

papyrus, is kind, but has no-one else other than undyne and Sans; Yet he dreams of being a Royal guard for the **fame**.(which he can't be because of his **LOVE**). Another example of a Friend deal.

he can't kill, his death is literally him using kindness to try and stop you.(I think **you** know how that went).

he's strong, but his LOVE makes him weak. 

he asked for love and lost his fame.

FRIENDS DEAL IS A BALANCE.

you ask for something, and depending on which category it falls, you'll lose something just as great as your wish.

LOVE or FAME?

PINK or GOLD?

(fun fact: you can do the same for toriel and asgore. it's pretty easy to spot once you follow this pattern)

I was gonna do the same for gaster, but his case in specific feels like an exception, where he asked for both and lost both. I don't know if it makes sense or if it's a stretch, so I'll probably leave it at that.

I can't get this outta my head so have this crack theory. SANS AND PAPYRUS IS ANOTHER EXAMPLE OF FRIEND'S DEALS.