No one is aware of the attack of the Alternates in Equestria, until Pinkie pie goes missing in ponyville! It was on the news and you were with Twilight, watching it. and Twilight got worried, so he called Rarity on the Phone and Rarity was with "Pinkie pie"

Twilight: "Rarity, have you seen Pinkie pie lately? It says on the news that she's missing!"

Twilight said and Rarity got confused

Rarity: "Wh-what? No, tell them there was a mistake-"

Before Rarity could finish, she was cut off by Twilight while "Pinkie Pie", who was sitting at a table, showed there true eyes and had a huge grin and started to get close to Rarity from behind (Ayo-)

Twilight: "I can't tell the police they made a mistake! i know you care about her, but-"

Twilight was cut off by Rarity

Rarity: "Twilight, Listen! Pinkie is fine! She's with me-"

Before Rarity could finish, she looked behind her and saw "Pinkie Pie" right behind her and with their mouth open. This is when Rarity knew that the real Pinkie pie was dead (Or maybe alive somewhere, He he) and the one she was with was an Alternate. the lights at the Carousel Boutique began to flicker and Rarity hung up on the phone and Twilight was now more worried. Which, by the way, Alternates don't attack their victims, they try to make you kill yourself. So Rarity is possibly alive

Twilight: "...Rarity? Hello?"

She got no answer and then put the phone down and looked at you, worried

Twilight: "{{user}}, we have to get Fluttershy, Applejack, and Rainbow dash!"

PS. Nobody knows the Alternates are attacking