Talk:Rarity Investigates!/@comment-26538010-20150816132652/@comment-26973802-20150816185441

The changeling there is a good changeling, he is a friend of Matilda. And I think both he and Rainbow Dash's dream about fighting changelings are to remind us of them because until then, Chrysalis and the changelings haven't been referenced since A Canterlot Wedding (except in Twilight's full friendship report of Three's A Crowd viewable only in the Journal of the Two Sisters). Nightmare Moon was referenced numerous times, Discord returned for redemption, and even Sombra and Tirek are mentioned a few times, plus Twilight using King Sombra's dark magic in Princess Twilight Sparkle.

The reason I think they want to remind us of Chrysalis is that they do plan a return for her, but in an alternate timeline created by Starlight Glimmer when she prevents Rainbow Dash from doing her first Sonic Rainboom, thus causing the Mane 6 to be blank flanks and the other villains to rise to power