Big spoilers for Suikoden 2 end-game events and the good ending.
There's something i find to be a weak point in the otherwise solid story of Suikoden 2. It's Nanami's reasoning to leave Riou after the Rockaxe events, if she survives. I couldn't find people talking about it much, so maybe it's just me, maybe i'm missing something. If you find her decision to be logical, please explain it to me.
Through the entire game, Nanami appears as a cheerful and brave character. Though she feared of ghosts etc and often wanted to run away from the war, she was no coward and her drive to protect her brother was much stronger than any fear she may have had. Yet she's a different person after the Rockaxe events, her decision comes as selfish and cowardly. Riou may be suffering from having to fight his friend no less than she does, so why put him down even more by faking her death, why not give him the moral support when he needs it the most? In the dialog between her and Shu, the normal portrait is used, so it doesn't look like she's still in physical pain. She says something about when she saw him trying to protect her from the arrows, she realized that he's too important for that, a leader shouldn't be like that. But wasn't she the one to urge him to take her on the Rockaxe liberation mission, like nearly all other missions? So why not simply stay at the castle from now on and beg him to do the same? Did she seriously think he would stop fighting and risking his life while she's away? He rejected the run away idea in Tinto even when she was around, so now nothing would hold him back from fighting, other than maybe mourning her death (if she counted on that, that would have been really cruel of her). I doubt the writers intended to portray her out of character like that, i think they simply failed to come up with anything more convincing.
Here's a random idea of mine on how the ending could have been with Nanami staying within her normal character. While dying, she had a vision from Genkaku, but it was interrupted by Huan managing to save her. Overwhelmed by the Riou and Jowy confrontation, she gets the idea that maybe if she prays at Genkaku's grave and speaks to him again in a vision, he'll tell her how to stop her friends fighting and end this war. She decides to sneak into their home in Kyaro. It is still under Highland control, so it's very dangerous (i don't know why in the actual dialog they pretend that it's easy to get there). That's why Riou must not know about this, he wouldn't let her go no matter what. She gets caught and we won't hear from her again until the good ending. In the final Riou and Jowy duel, Nanami shows up in the last moment to stop Jowy finishing off Riou (the duel actually waits till Riou's HP is critically low). Now that would have been an epic reunion of all three. Then the runes start reacting and so on, like in the original game. Then either her or Shu (like in the original game) tell us the whole story. After Highland fell, Kyaro was liberated and Nanami was free, she didn't realize yet the war was really over and went on with her vision idea. Genkaku told her to go to Tenzan Pass quickly, and that's how she did stop her friends fighting, just what she prayed for.