Hue hue, we know why I am here of course. Mercymaker is one of my absolute favorite ships for Angela, and honestly I think it would be a great deal of fun for us to explore and develop so long as we are both interested! Angela is obviously very focused on her work, and always has been, but since she is more of a pacifist than anything, when she was working with Overwatch in it's initial run, she was very fond of the company she could keep with others who brought her peace, and I like to think that Amelie, as Gerard's wife rather than a member of Overwatch itself, was one of those people for certain. As well, Angela has a definite interest in the arts, especially of classical music and dance, so I am sure she enjoyed watching Amelie dance, a la that art by Atu.
Which of course takes us to post fall, where Angela would have been pretty devastated to lose Amelie to war, essentially, just as she lost her parents, Jack, sort of Gabriel. Angela operates on logic, and given that Amelie was brainwashed and altered as part of who she is now, Angela works on the assumption that it could be reversed in a sense, with enough research, but even if that were the case, there would be a lot of emotional and mental scarring left inside of Amelie if it was possible.
Bringing us to current day, where Angela is very much missing her companion, someone she was very fond of, and wanting to believe that they cannot be stuck at this stalemate of opposing sides forever, and she wants her Amelie back, meaning she is probably willing to take what she is given, resulting in a lot of push and pull.
I think a very fun thing to explore is that push and pull dynamic, where Amelie/Widow is likely to be cold and manipulative- intentional or not, and Angela is trying to fight for her in a way, and to fight with her own emotions which could easily be toyed with. She wants to help Amelie heal, wants her to feel human again if possible, and she wants to be by her side.