In "Little Mustachioed Shit", flashbacks show an early sexual encounter between Alex and Piper, at Alex's home. Alex's phone rings, and she leaves the room to take the call. A hooded figure enters the room seconds later, and launches at Piper, attacking her. Hearing Piper's screams, Alex comes running back in and drags the figure, which turns out to be Sylvia, off Piper.
Piper is frantic and shouting at Alex that the woman attacked her, and just broke in, to which Sylvia shouts "I live here!". An incredulous Piper realises that Sylvia is Alex's girlfriend. Sylvia shouts to Alex to get Piper out, to which Alex responds "I will, and then we're gonna talk". Sylvia storms out and Piper and Alex have a short argument whilst Piper gets dressed. Alex claims that her relationship with Sylvie is complicated, but Piper doesn't care, and when she can't find her shoes, leaves without them.
Piper and Alex later meet again in a bar, and start talking. Alex says she's new to this "whole relationship thing" and she wasn't lying when she said it was complicated, to which Piper says that she doesn't want to stand in the way of true love, and if Sylvie is her future wife she will back off. But, she says, Alex pursued her, and she liked it. The pair end up hooking up in a bathroom stall.
Later, Piper is discussing the situation with Polly when her doorbell rings. She opens the door to find a flaming brown bag, which she stamps on, and discovers it is full of poo. Polly is nonplussed, claiming that's the oldest prank in the book. Piper knows it was Sylvia, and is frightened over what she will do next.
Piper and Alex are shown in bed again, where we learn that Alex left Sylvia for Piper. Alex says that Sylvie just needed to rage and will not come after Piper again. Piper asks, "did you love her?", to which Alex replies, "No. But I love you".