Ash didn't comment on Nico because her brother was the least of his worries. He could honestly say he did not give a flying fuck as to what Nico thought and likely would never. And if Bella wanted to let Nico hate on their dad more, bully for her. Though their dad wasn't around and Ash knew full well that when someone was mad, they wanted someone nearby to be angry at. But again, Nico meant so little to Ash that his anger wasn't a concern.
The blush, however, drew a quizzical eyebrow upward. Did she and Nico have a thing? But no, her face only turned a brighter shade (blushing was something Ash was good about noticing), and the name Misha Meru escaped her lips.
Ash didn't say anything at first. Instead his lip tugged into a smirk and then it transformed into a full grin. "Misha Meru, hm? Now, why would Misha Meru care? You do realize he's got a reputation worse than my own."