The friends we take for granted are often the ones that leave the largest impact on our lives. When Spike falls seriously ill with a mysterious disease and the ponies strive to nurse him back to health, Twilight Sparkle comes to grips with this very realization about her number one assistant--and friend.

EDIT: So this little story made it on Equestria Daily on 10/8/12. Now please excuse me while I pass out on Rarity's fainting couch while murmuring a soft Fluttershy "...yay."