She's full of anger coupled with sadness and the roller coaster of emotions are enough to make her feel like there's nothing left in Lima for her. Santana's reaction to Finn's death - a character piece based on Santana's role in "The Quarterback". Spoilers for episode 5x03.
There's no reason for Santana to be on a stage singing "Don't Rain On My Parade", except that she's determined to ruin every single thing in Rachel's life. That's exactly what she's doing. And Rachel knows in that moment that the one girl that she trusted is now her biggest enemy. Starts with 5x09 and veers off from canon beyond 5x10.
Alison is alive and back in Rosewood. Emily has to confront feelings that she has suppressed for longer than she can remember. Based on episode 5x05 and the fact that I needed to write something following that epic kiss.
Rachel and Kurt help Santana and Quinn move in together. One shot set in my "you got me wondering (will I burn or implode)" 'verse.