The house was something for Isaac to try and get comfortable with. After so long in the apartment, he'd gotten comfortable. As much as Isaac loathed small spaces, he didn't really care for wide open ones either. The noise was reduced a hell of a lot, and the freshness from the fact that they had a garden now, front and back, was moderately relaxing too.
He was astoundingly aware of just where everyone in the house was most of the time; from Anna and Kenzi's antics to Elsa's quiet presence to the occasional wandering. The wandering didn't bother him, it was fine really. Added a little noise to the house when it was quiet, gave Isaac a little white noise to tune in and out.
He didn't actually mean to go on a wander himself and bump right into her. "I'm fine," it was practically automatic, "Are you?" He was a little more sturdy than Elsa after all. "Sorry, I was... I wasn't paying attention." Which he should've because he already knew Elsa was having a wander.