This is an interesting question, in my 600 hours the only characters I’ve seen have romance starting dialogue outside of the Act 1 party is Lae’zel and Shadowheart. Lae’zel got an exclamation bubble above her head after I fought the owlbear, where she basically says what she says at the party but potentially sooner than the party (this didn’t trigger the sex scene till the night of the party even though she asked way before). And Shadowheart gets a dialogue that says something like “I feel we missed a chance to connect” but I’ve only seen that dialogue actually appear a handful of times, I imagine if you kill Minthara you won’t be in a relationship and thus the dialogue should trigger for you, though I might’ve actually been in the shadowlands actually when I got it, I don’t recall exactly. Wyll will try to seduce you with a dance in Act 2 which I believe starts his romance. But I’ve never been able to start a romance with Karlach, Gale, Lae’zel, & Astarion post Act 1 if I didn’t ask during the party.
Minthara’s recruitment only relies on the fate of the Grove and if she’s alive of course. You can take either direction, or even do both, which is what I usually do for extra XP.
This may not be the most optimal but I think a party of rangers, each with their own color dye would be fun. This way you could be the “power rangers”
I actually got surprised myself on another playthrough just yesterday where I was doing pure evil, but she decided to spare the nightsong anyway, which didn’t happen last time I did an evil playthrough. Maybe it’s random in some way, or maybe there’s a dialogue you need to have during some point that I missed this playthrough. I do know if you destroy the grove she becomes clearly upset about it during the party in camp, but I neglected to speak to Shadowheart almost entirely this playthrough so it’s possible I missed some dialogue trigger. I’m not sure myself now
Fun fact about the companion quests, what descisions you make as the player will change what your companions do if you let them make their own descisions. For example, if you side with the goblins and destroy the grove then Shadowheart will actually not reject Shar if you let her make her own decision.
I think it’s dark souls cause the woman on the left looks like the emerald herald