For a moment, Dave isn't sure why Bro is retreating - is taken aback by it because Bro Strider does not abscond, so surely it must be some sort of new tactic to catch Dave off-guard. Some sort of feint; and if Dave takes the aggressive approach now, leaping after Bro, he'll suddenly find a cascade of smuppets raining down on him from some shitty wire trap Bro set up earlier. Then he feels the surge of power that comes from the emotions he's getting from Bro, and he...

...well, he's actually not sure what to do with that. He didn't think any of this would be all that effective on Bro. At the end of the day, one couldn't exploit emotions that didn't exist, and Dave had been sure that if anyone could be immune to Mobius's flavor of psychological warfare, it would be the cool, unfeeling ninja that is his older brother.

Not so much, evidently. He furrows his brows in confusion for a brief moment before it occurs to him that this isn't the time to mull on it and that what he should be doing is taking advantage of the situation now that he's sure it isn't a trap, so he leaps in fast, blade poised to strike again.