dude… the cover, the name alone tells it. Also him sometimes not having his piercings, and the locked door. Read. Sol
Also they did say that the other twin wasn't involved until later. He mentioned it started in April while they were already doing the friday meet ups. We aren't given a proper time frame but once you notice the earing changing and that weird break in between sex the first time and the cologne.
no but like theres no hints to this happening in the earlier chapters wtf??? this just feels like a random switch in the story tbh