Sans stares in horrors at the dying Flowey.
The yellow plant flower creature had been placed on the floor while the desk was being cleaned, and the skeleton failed to see the pot. He had been carrying a large glass of salt water, which he normally uses to clean his jaw bones every evening.
However, he had dropped the glass when he walked into the pot, the salt water soaking through the soil quickly, damaging the roots and making the stem droopy.
Sans begs the evil flower plant thing, to keep 'living', begs it to open its eyes and glare at him, shout at him, do something other than continue to look soulless... er lifeless.
The only reason he did was not for the plant's sake but for his brother's sake -Papyrus liked the stupid thing since it was his first 'friend' he made in the underground (Sans didn't count since they were brothers). If the thing died then Papyrus would be heartbroken. And that was something he could not allow, not when it seems that at last, they were truly free.
Sans's highly intelligent mind clicked into gear for the first time in aeons. It went through all the ways he could save the creature in a moment of time.
Grinning like mad, the skeleton stood with pot in hand. Determination filling his bones as he slips into the endless void.