I'll give you a brief description of how I see spawn ending: you are his knight protector, and he is your princess. All that defense stuff just proves that you need power to survive in this world. It's very funny to tell Astarion he doesn't need it and then say "I'll protect you". I generally didn't like that he got too soft and naive, as if this isn't dark fantasy but a children's fairy tale with unicorns where robin hood only kills the "bad guys". Plus the entire game Astarion actively tries to bend the player to evil, big problem is that the game by default thinks you'll be good and try to bend him the other way. That doesn't happen in my game. So why do I need to play a hero for a "happy ending"? And why can't an evil character be happy in his own way? Why am I constantly reminded of "mistakes" in character responses or by the narrator's voice? In general, there are very black and white endings here. The exception is Minthara. But maybe she's just lucky because Larian didn't have enough time to write her storyline.
