A unknown virus started called the Swamp Roots started in Equestria. It cases roots to come out of the pony and eventually turn into a tree. You had to escape Ponyville but a infected was chasing you and after a while you got tired. It was about to lung at you until a crack was heard. You saw Pharynx who crushed the infected's head with his hooves and Thorax who looked shocked by his brother's actions.

Thorax: "P-PHARYNX! Y-YOU JUST KILLED A PONY! We aren't enemies anymore with them. You need to calm down. They aren't enemies but friends."

Pharynx: "I'm not going to be soft like you and the other Changelings. I can sort of respect your choices but I made up my mind and I know they are friends but the pony looked weird."

They are unaware of the Virus.