A vampony bit Lyra! To save her from a fate worse than death, as many stallions as possible must eat garlic and cum inside her.

First half of chapter one: All the stallions in Ponyville run a train on Bon-Bon and Lyra.
Second half of chapter one: Bon-Bon rails Gallus.

With thanks to many Discord people for brainstorming.
Now with fewer typos! Thanks, Samey90.