In chapter 26, Rena learns of Neene's possible connection to the Kanshuu and decides that FLAG needs to be informed about situation. Riku is obviously not too keen on the idea, and they both activate their Jinki forms in preparation for a fight. Just before things can turn violent however, Neene diffuses the situation by slapping Riku in the face! Though what she says next is the real kicker: "That's not nice! Papa!! Mama!! Don't fight anymore!!" Riku and Rena stare at each other for a second processing what they just heard.... Then promptly Freak out. (In fact, the shock caused Riku to transform back to his human form)
In chapter 90, Riku ends up with Neene and Ende clinging to him over who he belongs to. Rena is not pleased.