The Emperor is several hundred years old, so I think the difference is HUGE. The Emperor is much more mature, pragmatic, stoic, cold, and detached.

Fortunately, this wall began to gradually crumble after he became an Illithid and the Emperor's Right Hand.
Xal trusts him, perhaps more than anyone else in his life.

Deep down, Xal is still a frightened, crying child, covered with an impenetrable shell.
He lacks experience and is somewhat afraid of gaining it, because he believes it will make him vulnerable.

Xal had to endure an extremely difficult and painful childhood in both of his lives, so his experience is based solely on that. He has absorbed too much selfishness and the conviction that no one will ever help him except himself.

And if it doesn't work... well, that's even more fun.
He could write a book about it, I think.

The agonising fear that the Emperor will somehow be killed and Xal will be left alone also leads to paranoia.

At the same time, his life power also rapidly runs out while the gate is open. He has only done this twice, and each time afterwards he took a very long time to recover.
That is his limit - paranoia and despair. The threshold beyond which death or insanity awaits him.

I'm just wondering, would they kill each other in pursuit of tadpole power or not?

His companions were tools to him, because he was no fool and understood that alone, his desire might never be fulfilled. So he used them, and when they became useless or dangerous, he eliminated them.

He also wanted to find himself, his missing part. He did not feel whole, and this drove him crazy and caused him mental anguish.

Xal saw it as a challenge, not a challenge to him, but a challenge from him to everyone and everything.
He wanted to live and live freely, and he was ready to make any sacrifice to achieve this.

Kea is my OC from NWN1.
I can't stand LG paladins, and he was supposed to be a joke character, but the joke went too far.
Something terrible happened — I grew fond of him, even though I still hate LG paladins.