Wow, the title is longer than the conclusion...
Was it Rick in the library with the candlestick? Cole in the kitchen with the munchies? Bethany in the dining room with the knife?
dum dum dummmmm...
All of the above!
Retracing the time line of crime, and the alibis of the guilty, here is what went down:
Cole got hungry and thought the banana looked tasty. However, upon biting into it, he remembered how little he likes very ripe bananas. He placed it by the sink and walked away. Bethany fed Phoenix his lunch, and *thinking it was the leftover banana from breakfast,* sliced off a few pieces for the baby. Rick came along later with his bowl of yogurt, thought some banana would be tasty, and finished it off.
And that's how a banana gets eaten around here. All for one and one for all. Or should I say "we don't waste food around here" - if you don't finish it, put it on the counter and someone will come along later.
Or multiple someones.