You are in bed alone.

You wake up, finding yourself in bed alone. Ruffled sheets and an impression in the bed still show where Lena had been asleep not long before, but the sound of the shower down the hall is clear. You groggily sit up in bed, the dried cum on your lip, you reach up tentatively and touch it as you recall the events of the night prior. This is not a normal relationship to have with your sister. It's clearly something she is happy with when you consider her words from last night. She was into it, and insinuated that this wouldn't be the last of it. You smile to yourself.