#mod tuffnut

The only people he doesn't anticipate at the final battle are, in order of least to most anticipated,

1. Sir Sparklepuff

2. Runaan

3. Zym

He isn't surprised by Ezran bringing Zym. He, however, doesn't realize Thunder's unfinished business is his son, despite him demonstrating to Terry that it's the easiest way to tether someone to the In-Between. Thus, he doesn't expect for Thunder to break free and fight him.

It's unclear if he knows that Runaan is Rayla's dad or just her troop leader so to speak, but he likely thought either way that Runaan would go home to his husband. When Runaan steps out dramatically with his bow trained on Callum, Aaravos actually hesitates because he knows Runaan IS a killer and would follow through when Rayla can't.

Lastly, his LITERAL son, his own creation, shows up and surprises him because he didn't believe Sir Sparklepuff had a soul. Aaravos gave him one purpose: lead Viren and Claudia to his prison, aka him. It shouldn't be surprising that he is still seeking out his "dad" because he died before he met Aaravos. Yet, it's the final nail in his coffin because he forgets about family. For all he playacts with Viren about "our son", he never believed Sir Sparklepuff had a real consciousness.

In fact, Sir Sparklepuff's appearance most likely caused Aaravos to lose focus for just long enough that he lost control of Thunder. It's the last in the rule of threes, being closest to Aaravos personally. Sir Sparklepuff literally lands on Aaravos' nose to show him what he's been missing this entire time.