Kylo Ren kidnapped and attacked her. Rey fought in self-defense.
You know who else he kidnapped and attacked? Poe Dameron. Kylo tortured him to steal the location of the map/BB-8 from his head and during that interrogation Poe had zero way to defend himself. Unlike Rey, Poe couldn't turn the force against Kylo.
And yet this interaction is brushed aside when Reylo gets brought up. Somehow Kylo's actions weren't as abusive in that instance...? Why aren't we also talking about Poe's abuse? I don't get it. Kylo invaded his mind so ruthlessly that he was barely conscious by the time Finn found him.
Her ability to defend herself against abuse does not make the abuse okay.
Oh I don't doubt that his actions were wrong. But think about this. By the time he first hears about Rey from Mitaka...
He grows increasingly frustrated; nothing has been going right for him, and Snoke is aware of all his failures.
And then all of a sudden, there's this girl who just helped that same stormtrooper and droid escape from the FO yet again. Who is she and how did she manage to escape? For all he knows, she is an active Resistance operative with secrets he can mine. Why wouldn't he try to capture and interrogate her just like he did Poe? The point is:
She helped the Resistance so she is an enemy of the First Order.
In Kylo's eyes, the Resistance is a state-sponsored terrorist group. When the US government caught members of the Al-Qaeda, they didn't hug it out and treat them to a buffet. What they did was imprison and interrogate them to gain key info about their operations.
Where many people see the interrogation scene as an unspeakable scene of victimization of Rey, many others see it as evidence that Rey is not only his equal, but is actually more powerful than him. –source
Torture and interrogation is a thing in Star Wars. See 1 & 2.
That "compassion" includes kidnapping her, killing her father figure, throwing her into a tree, putting her best friend in a coma, and attacking her.
Already addressed that above. Kylo had a personal vendetta against Finn after he betrayed the FO. He didn't kill Han just because he knew Rey saw him as a father figure; he had his own messed up reasons to do that.
Also want to point out that the filmmakers included two interrogation scenes in one movie. Why? To help underline the contrasts between them. Can you really say he treated Rey worse than he did Poe in those scenes? She left unscathed and actually more powerful than before (cool, I can read minds and control people now!!).
Kylo's entire schtick is trying to pretend to be something he's not. That's why Ben Solo got a new name and a new helmet which also happens to mask his voice. Every one makes fun of him for being a sucky Vader-wannabe, because it's true—he's terrible at being the bad guy (see list of failures above).
Han forgave him and he must have had good reasons to...
Kylo had a support network.
Adam Driver and JJ Abrams disagree with you:
A: "If you really imagine the stakes of him, in his youth, having all these special powers and having your parents kind of be absent during that process on their own agendas, [being] equally as selfish, he's lost in the world that he was raised in, and feels that he was kind of abandoned by the people that he's closest with. He's angry because of that, I think, and he has a huge grudge on his shoulder."
JJ: "So this mother and father had a target as a son, someone who's watching their boy, and these parents aren't there enough to guide him."
Snoke groomed Ben Solo from a very young age to be his weapon, and did it so well that even Han, Luke, and Leia couldn't protect him. Think about that.
Nothing about Rey's story or personality suggests that she would have any motivation to bring Kylo Ren back to the light side.
Just going to quote u/sushivernichter here because they said it better than I could:
For me the allure is kinda BECAUSE Rey has no obligation to forgive Kylo. She is unattached, unrelated and if she hates Kylo's guts forever, noone could blame her.
So if she chooses to forgive him, see anything but a monster in him, it won't be because she feels obliged to her long-longed for family. It will be a selfless act of kindness and mercy on her part. It will have more weight precisely because she freely chooses to do so.
