So first thing I notice is the lovely layout and banner :) Second thing I notice is that the first line doesn't make sense. As I was sliding the last tray of cookies into the oven when I heard my older brother walking into the kitchen. - either get rid of the 'as' at the start, or the 'when' and replace it with a comma. Quite a lot of the dialogue was funny and I do like how entertaining it was. I could really picture the playfulness of their relationship happening right in front of me, which is great. The prompt was used brilliantly. What Johnny said was hilarious and I could really feel the awkwardness and embarrassment and humour and oh-my-god-did-that-really-just-happen? feeling and it was just awesome.
And with that my older brother who I was now plotting the murder off.... - should be 'of' not 'off', but otherwise I love that line lol The air was so thick in the kitchen that I could slice through it with a knife and barely make a dent in it. - with this, I get what you're trying to say, but it kinda doesn't make sense, you know? If you sliced through it, surely you made a dent of some sort lol “No what do we do?” - missing a 'w'...
I wanted to etch this moment into my mind and keep it forever. - I liked that line a lot :) I think it really completed the beautiful passionate moment. I really adored this short story. I wish I had more to say, but there isn't really anything else to say apart from I really freakin' liked it. Congratulations on writing such an awesome piece :D