Knowing that Prometheus is a giant and actually seeing it with his own eye are two different things, and Thor is actually delighted to see that his friend is actually taller than most of the giants he's fought before. Surtur had only been about half as big - the first time, anyway - and none of the Jotuns had come close. Their beasts, on the other hand, definitely had.

Idly, Thor muses that it's a shame that they don't have a Muspelheim dragon to fight together; it'd be a fairer and more honorable fight than taking the beast's head off with the Bifrost. Ah well. Maybe next time.

His first few attacks are experimental, testing hefty punches against the soft spots of one of the titan's ankles, seeing just how much of his strength is going to be needed to even make Prometheus flinch, long before he tries to knock him off his feet. The immense difference in scale is forcing him to pay attention to his position, as well, unable to rely on his experience with more Thor-sized folk to judge the distance accurately. All the same, he's well aware that he's in prime position to get stomped on, watching the shift in the titan's shadow to guess if there's a big ol' foot headed his way.