Wow that's cool. I can't imagine why a monarch would interact with a dusky wing like that. How big was the dusky wing?
Once I saw two monarchs swoop down on another monarch in mid-air, and all three hit the ground. When I found them, it was two males and a female. One of the males had attached to the female, and was trying to fly away with her. The second male had a grip on the female too and was trying to displace the other male. Then the first one took off, carrying both! I was shocked, but now I know one monarch can lift two other monarchs.. just barely, in short hops.
Eventally the second male gave up and fell off, but continued to dive bomb as the freed pair made for a tree top.
As for interaction across species, I've seen monarchs in fields go after birds like they would if they were going after another monarch to check out. The birds usually ignore, as far as I can tell.
I've also seen a painted lady trying to mate with a (male) monarch, following it from flower to flower for like 10 minutes and being completely ignored. I actually have video of this. Hmmm.. maybe I should get some human friends :)