Okay, not my favourite chapter here in Chapter Four, and I'll tell you why.

Problem the First - Flashback scenes which don't tell the story.

Okay, yeah, like Jet. But this isn't his story, and this isn't going to influence the story. This is, to put it less politely, a waste of space. Conservation of detail is something you have to worry about. We don't care that Rainbow Dash is Jet's friend. We don't care that Dusk's dad knows Rainbow's parent. That's because neither of those characters are a part of the story.

Problem the Second - Importance of Characters.

You know the old stereotype of Mary Sues? Someone makes an original character and inserts it in a fan fic, and suddenly, every major character is obsessed with them - even if it makes them out-of-character.

Rainbow Dash goes out of character for this. She's being shipped with a character who isn't even an important character in this fic! There's no time for explanation, there's no time to explore what happened to cause this, there's no reasoning behind it other than that they were friends, and we don't even see why! This is like hearing, in Star Wars A New Hope, that off on the other side of the galaxy, the Emperor is having trouble with pirates. So? We don't care about the Emperor, we don't care about pirates, we don't care about the other side of the galaxy, we care about Luke Skywalker rescuing Leia and blowing up the Death Star.

Problem the Third - Wasted Opportunity.

Conservation of detail. This chapter could have explored the past by letting us see what Dusk's new friends are doing and his comparing them to Jet. Petal tries to act boyish to try and get Dusk that way, and he remembers old Rainbow Dash and how Jet called her one of the most boyish fillies ever. And that reminds him of why Jet left.

See, that has character development, plot development, character history, and even ties in with the show itself. That's why that's under 'Wasted Opportunity'.

Well, that's basically it. Technically well executed.