My younger sister, who is usually treated like a child, suddenly starts acting all maternal and helpful when our parents ask her to 'take care of things while we're away.' She's seven years younger than me, but she starts doing chores, being overly nice, and fussing over me. Her outfits are super revealing, showing cleavage and panties! On days I get an erection from seeing this, she says, 'You're such a caring big brother,' while acting annoyed, but she's actually very happy to suck on my erect dick!
