I found it. Here’s where to get it from my context:
<RatingOne @scaleValue={{this.scaleValue}} @topic={{this.parentView._parentView.topic}} />
So I’m able to use that parentView and _parentView to work my way back up to the topic! That’s the magic I’m looking for, (which I think will also solve another issue on another project). Now all I need to do is put the stuff in the topic controller, which is all hopefully stuff that I (at least mostly) know how to do!