Moved Apartments - Cat Behavior/Appearance Change

Let me preface this by saying I know even the slightest changes can send a cat into a spiral both mentally and physically. I'm mostly looking for reassurance, I guess...

I have 2 cats (10 months old, brother and sister) and we moved to a new apartment 2 weeks ago. Over the past 3 days Graham (bro) has started acting like he's in a toddler "Mine!" stage.

He doesn't want Hazel (sis) to be around me or anything he wants to be around. He was never like this before. In fact they've been inseparable, lovable, and playful since birth.

I figure this is him trying to assert dominance in a new space.

What concerns me most is actually Hazel.

She's looking kinda... scraggly.

As in, it looks like she's not maintaining her coat, she's sleeping a bit more, hiding (obv from Graham not me), and I'm just worried.

Both eating and drinking enough, using the litter box, no respiratory issues or other illness related symptoms. Just... a newfound jerk-y side and recluse behavior.

Thoughts?