High five for weird hours and pacing the deck! Ari sometimes watches Natsuno's movies with him so Clarke may have heard her commentary on the stupid behavior of horror movie protagonists too.

Ari's also worried about potential supply problems (that there always seems to be food just there doesn't mean there always will be!) so she'll be grabbing long-life snacks and useful resources too when she can. They may sometimes be in competition!

Probably all the exercise things. If Clarke prefers the stairs, she's likely seen Ari running up and down them sometime (Nobunaga got her to do it once, she sucked because cardio's not a priority on starships, she decided it was a weakness that needed fixing).