@Wizard of the Coat
You touched on several things I was going to suggest. Neat! So, basically I get the impression that both characters have similar outlooks on life. The Venn diagrams are probably almost entirely overlapped. Their histories are probably just as similar. I have zero doubt that they both would have gotten along swimmingly--probably much to everyone else's chagrin. Andraste didn't grow up with other children around, so Copper makes a logical fit for friendship.
So instead let's focus on the thin sliver of differences. What's a story without conflict, right? Seems like Andraste had a weirdly stable orphan childhood. She was surrounded by people who took care of her, gave her an education, and weren't involved in any shady business. She was pretty sheltered from exploitation. Reading about Copper I get the impression that she is probably WAY, WAY more world-wise than Andraste--both in a good way and in a bad way. Andraste romanticizes n'er-do-well, rakish scoundrels. Copper actually lived that life (even at her young age). The contrast between exciting stories and the danger of reality may be a source of tension between them. Andraste might be older than Copper, but I think Andraste (foolishly) wishes she had the exciting time growing up that Copper had. It's a miracle Copper has such a positive outlook on life, which is something they both certainly share in.
Thoughts?