Big City Infection AU [Original]

[Clarification: this Au was created by me, so it is original, I saw that they took the Mlp and other fandoms in these Au infections, so it was the turn of this series to be placed in the AU infection plot]

(The story is being created and the ending is in process. The clarifications are that all the work is done by me, I will only tell the story and explain the plague)