When Spike gets into an Accident Rarity attempts to rebuild him as Spike bot, but Twilight refuses and demands Rarity let her do it, after a short fight Twilight's magic mixed with Rarity's tech turns Spike into a living virus and quickly drives him insane, it's up to Sweetie Bot to keep him at bay while Rarity and Twilight try to find a way to contain him.

set in an Alternate Universe where Rarity is a Robotics engineer instead of a fashionista.

my 50th story (art has been added to the story thanks to ZettaiDullahan