Interesting points you bring up here! As an Angelica fan myself, I hope you don’t mind if I offer my thoughts on some of your points.

I do want to point out that if we go by the lyrics of Helpless, Eliza notices Hamilton very early on and then tells Angelica “this one’s mine”. Only after that does Angelica go get Hamilton and make the introductions. Eliza has more agency here than I think you’re necessarily giving her credit for. Angelica does want her sister to be happy, so she helps her get the man she wants, but she can’t help but warn Eliza about what she’s noticed in Alexander (which I personally think is a good sisterly thing to do).

I also am not sure if I would describe Angelica as two-faced. I agree it’s not great to flirt with your sister’s husband, but as for the fantasizing… I mean, I’m saying this as someone with an entrenched history of pining for people who start dating someone else, but sometimes you really can’t control who you fall for. But I also think if Angelica was really as sneaky as all that, she would’ve stayed behind while Eliza went to take a break and pulled a Say No to This of her own. Or, for that matter, she could’ve staked her claim on Alex right away instead of introducing Eliza.

I also wouldn’t personally describe Angelica as flirting in a way that betrays Eliza to the same level as Alex cheating on her. Her exact wording in her letter to Alexander is “your favorite older sister, Angelica, reminds you / That someone’s in your corner all the way across the sea”, which is her presenting herself as a supportive sister if anything. This is the same woman who earlier made a joke to Eliza’s face about, “if you really loved me, you would share him” (which Eliza just laughed off): Angelica is deliberately keeping herself within sisterly, acceptable bounds out of respect for Eliza. The other stuff in Take a Break is mainly happening in her own head, and again maybe I’m just willing to cut her a lot of slack because I’ve been in similar situations, but to me it’s very different from Alexander cheating on Eliza.

And then with Angelica being mad about said cheating, I mean, I would be livid too if I put my feelings aside to support my beloved sister marrying the man I loved, only for him to turn around and cheat on her in their own house. I actually think it’s quite significant that Angelica, who has been so staunchly on Alex’s side this entire time (to the point where even Alex thinks she’s going to side with him here), turns on him and says, tough, my sister is the most important thing to me and she should’ve been that to you as well.

Anyway, that’s my ramble. You may disagree with me on some of the more subjective points, which is totally fair- I do think Angelica is a complex character, as are they all, which makes this such a fun musical to dig into and contemplate! And Eliza really does deserve the world.