@annethestorynerdgirl, Here are my thoughts.
You don’t want what is called “deus ex machina”, which is sudden/random intervention from someone or something, that has no background in the story, or if it does have background you want the reader to be able to go ‘Ohhh! I see it! That was so cool!’ not “Wait… How did that happen?” I’m not saying you are doing this (in fact is sounds like you are not) but it’s something you want to avoid.
If you are planning a sequel, sometimes pulling side characters to the spotlight can be a great way to go because you are connecting dots, from another perspective, and it gives the reader something to look forward to. You don’t want the two characters to be random, never heard of, you want them to be there all along (not necessarily in the spotlight), flickering in and out of the shadows. Think of it like you’re giving glimpses of the “gift” all through out the story, and in the climax out reveal. Does that make sense?
@daeus-lamb, that doesn’t go against anything you’d say does it?
Published author, reader of many books, Student in writing, and Lumenite!