These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Complete Monster: Fuhito is a scientist for the original AVALANCHE. His mindset can be described in a single expression: Hojo's his hero. In addition to that, Hojo likes him a lot enough to seriously consider leaving Shinra to work with the guy. Fuhito found a way to copy part of Shinra's SOLDIER program. With the data he invents his own variant complete with monstrous degradation of the mind and turning the subject into monsters. He takes two of the SOLDIERs Zack later remembers and turns them into abominations on par with Hojo's aberrations. He later finds an ancient Ultimate Summon that has been broken long, long ago. He implants a piece in an innocent girl, transforming her into a weapon to be AVALANCHE's spearhead against Shinra, while the piece starts sucking out her life to rebuild itself. He establishes a firm powerbase to release the Summon, which is to burn the entirety of the world. In the end, he winds up taking it all and merging with it. We all know what happens when you do that.
Hilarious in Hindsight: When Cait Sith is introduced he's easily damaged and is nearly useless in a fight. Reeve is frustrated but later has an idea to improve Cait Sith's fighting capabilities. Consider how useful he was in Final Fantasy VII - that was after Reeve upgraded him!
Magnificent Bastard: Rufus. He's the one controlling AVALANCHE for most of the game in order to discredit his father and make Shinra look bad, and many of AVALANCHE's attacks, such as sabotaging the rocket into space, are done to further that goal. Why? So he can take over Shinra. And he's a Karma Houdini to boot, since the President can't admit that the Vice-President and his own son was scheming with his enemies right under his nose.