Scrapjack is an expert alchemist specializing in colorful explosions. She loves anything that makes noise, flashes bright, and roughs up the nearest elite pony. Being born without wings made her a reject in the eyes of her mother, so she was unceremoniously dropped off in Equestria and left to be picked up by the next pony who walked by. That ended up being a sweet young baker who was more than willing to take her in. They named her Strudel and cared for her until she was old enough to run off with Rotgut.
The yakicorn in question is 800 pounds of raw power and sharp intuition. She's observant as a hawk and quick as a fox despite her size, and her main goal is to keep Scrapjack out of trouble. Don't get her wrong, Rotgut is as much of a chaotic force as her (comparatively) tiny friend, but Jack has a hard time knowing her own limits. She'll easily push herself to the edge if Rotgut doesn't intervene. She also functions quite well as a meat shield when the two of them are being pursued by angry unicorn guards firing fireballs and magic arrows. Her given name is Suki, but god help you if you call her that.
Update: Made a couple minor edits to better reflect how I draw these gals Update2: underbite scrapjack my beloved…. <3