I'd been waiting throughout the entire game to see what became of Isa once he got his heart back.  I figured he'd be off celebrating, or perhaps even join Sora and Lea against Xehanort.  Never in my wildest imaginings did I think he'd collaborate with Xehanort AGAIN now that he has his heart.  That was a bit of a shock.

 

So...what's he up to?  What on earth is going through his head?  The only reason he had joined up with Xemnas to begin with was to get his heart back, and even then he was wanting to overthrow him.  So, why join Xehanort now?  One theory I had, which might be pretty invalid, is if he were forced into the matter; perhaps Xehanort had made him one of his vessels of darkness.  I noticed Isa looked sort of saddened or grim when he blocked Lea's attack, which made me start wondering if his siding with Xehanort wasn't his choice.

 

What do you guys think?

He was norted. That's why he's helping Xehanort.

well he always was kinda a dick...

Yes. You're both absolutely right. The part of Saix that's still Isa doesn't actually want to hurt Lea, but he's at least half Xehanort by now. On top of that, MX has the ability to force his own consciousness into any one of his vessels. He may not have even attacked Lea then if MX's consciousness hadn't "possessed" him at that moment. 

Isa was cold as a human but not nearly as sadistic as Saix is as a Nobody/Vessel of Darkness.

He was norted. That's why he's helping Xehanort.

I never heard the verb "norted" before coming here. I'm using that from now on if you don't mind.

Good question! I'm not fully sure about this either, but now that you mention it, Isa DID look sad while attacking Lea. He probably was forced to join Xehanort. Either that, or he's just a dickhead lol we'll find out in kh3.

Besides, he has the recusant's sigil... permanently. If h tried to rebel against Xehanort, he'd instantly be defeated. He wouldn't stand a chance.

Besides, he has the recusant's sigil... permanently. If h tried to rebel against Xehanort, he'd instantly be defeated. He wouldn't stand a chance.

 

Isa is doomed, Recusant's Sigil like Kinode said.

He has the Xehanort's heart, so no where to run now motherf*"#%"!

OR maybe we just think there's this little bit of good in him when there isn't. There's also the possibility that his obsession with power outweighs his care for his ex-best friend

He's possessed. Possessed by Xehanort. But I've always thought he's in there somewhere. I mean, his face was... I don't know, like, Lea get out of here please because if you don't I'm probably going to hurt you.

He didn't scream like Saix, he was quite, and I agree with ElicaGreenstar, Isa didn't attack with all his powers and it can be noticed if u focus at the moment before Lea jump from the throne to the ground, plus if Isa would ever want to do something like stopping Lea, he would do anything to stop him, which he didn't do, plus his eyes are similar to the eyes of Terra when being controlled (not the eyes color), I mean the way of him being possessed and forced to do something.

i dont think hes being possesed, hes just kinda at war with himself. in KHll Saix was all like "Kingdom Heaaaartssss" before being defeated so that might be why hes with Xehanort is that even if he has a heart. well, actually, im not even dure if anyone else other than Lea, Ienzo, Aeleus, Dilan, and Even got their hearts back. maybe lea's mistaken and he's still Saix and trying to get his heart back