Oscar:
To get on the path you have to be in love with him, the necklace and being nice/romantic helps but afaict the key is to choose him at the river and pick "What about Cassidy?".
Good end: Be fairly nice/romantic, choose to marry him at the end.
Bad End: Be fairly nice/romantic, choose NOT to marry him at the end.
Normal: Be douchey, dishonest, domineering, overcautious and dismissive. He will dump you

Cullen: To get on his path choose him at the river and don't be a total douche to him.
Good End: Accept Callum's offer. Tell Cassidy to talk to her parents. Be nice to Oscar.
Bad End: Reject Callum's offer or tell Cassidy to talk to Pherod. Don't run off with Dolores.
Normal end: Go for Good End but treat Oscar like crap.
Dolores:
Good end: Do the Cullen path, be nice but entirely unromantic. Be nice to Dolores, tell her being alone is a weakness. When she asks you to run away with her say yes.
Bad end: Tell Cassidy to talk to Duke Pherod. Get Dolores to like you but not enough to trust you. Apparently one way is to kiss Callum in front of her then say he means nothing to you but be otherwise nice, I did it by refusing to untie her. Say being alone is a weakness. Accept her offer to run away.
Gaston: To get on the path, don't wear Oscar's necklace and check Gaston's room.
Good end: Be nice and accepting of Gaston and Cosette. Tell Cassidy to follow her heart, sleep with Colette.
Normal end: Tell Cassidy to follow her heart, don't sleep with Colette.
Bad end: Tell Cassidy she is Caspian.
Nazagi: To get on the path visit his room, don't get on any other path.
Good end: Be clever and helpful. Specifically, when he asks you to tell a funny story, talk about the guests.
Bad end: Get to the good end choice, reject him.
Normal end: Be insufficiently clever and helpful.
FOREVER ALONE: Pick Pherod's room. Talk to Oscar at the river and tell him you think of him as a brother.
The Oscar good end is sweet. I'm annoyed at Oscar for being so grumpy if you are kind but unromantic to him. I'm glad the normal Oscar end exists even if I wish there was a way to get him happily married to Cassidy and friends with you WITHOUT being in love with him or married to someone else.
I really liked the Cullen good end. I have a soft spot for sexy awkwardly well meaning but violent brooding guys. The Cullen bad end is a bit random but hey, you're in a dangerous situation, sometimes random choices get you killed!
The Dolores good end is even more random and arbitrary but was sweet. I felt bad for abandoning everyone but such is the nature of the path. I wish you had more chances to be friends with her before that.
The Gaston good end was...odd. Gaston is such a weirdo, Cassidy can do better, but they do seem happy. Also while I am very glad that there is a femslash option the Cosette romance was SUPER understated, not even a kiss despite my best efforts. Everyone else gets a kiss! You do get to be naked in a bath and share a bed which, yay, but still.
It took me a couple of playthroughs to NOT get the normal end, so my feeling of "DAAMIT NAZAGI I HELPED YOU" was quite genuine. Still, he was nice enough about it in his way and totally in character. And then...unexpected threesome! Which was very understated but sweet and I like to think it really did lead to a threesome ;)
I'm rather annoyed that the forever alone ending doesn't care if you are are thoughtless douchebag or otherwise decent and clever, you are equally ALONE. Also Pherod is the second cutest guy in the game I wish you got to know him better. (The cutest is Nazagi FYI. Cassidy is the cutest girl. Cosette is the second cutest LI. NOTE THE LACK OF SEXY MAKEOUTS WITH ANY OF THEM why does this always happen to me ;_;)
In general I enjoyed the game and how everything fit together, and am curious to know what happens in the remaining ends. I really like Cassidy and am glad she ends up happy and secure in her gender identity in most endings. Though a friend pointed out that "trap" is often used to mean "sexy guy in drag" which is unfortunate in context :/