who cooks normally?: Kyle, he likes cooking.
how often do they fight?: Their arguing is usually playful, any irritation easily quelled with joking and kisses. But when one of them comes home hurt things get tense. Not really anger, but worry and stern talking-to’s. Piers’ hero complex probably gets him snapped at by Kyle, and Piers probably gets frustrated with Kyle’s unhealthy relationships around Frolic.
what do they do when they’re away from each other?: Kyle goes to Frolic almost daily to appease Cohen. Piers uses the time to explore Rapture while collecting supplies. They probably spend a lot of time together otherwise.
nicknames for each other?: Generic pet names now and again, babe/honey. Kyle might jokingly call him ‘soldier boy’ in way of teasing him for certain things he says or does that seem stereotypically military.
who is more likely to pay for dinner?: I’m sure they’d switch off if there were an opportunity.
who steals the covers at night?: Kyle tends to cling and roll up in covers, so if he did steal them he’d be attached to Piers and still covering them both.
what would they get each other for gifts?: Kyle would go down to Neptune’s bounty and pay off some smugglers to get his hands on some real food. He’d make nice, big, healthy diners for Piers until the food ran out. Assuming Piers’ PDA had music on it, he’d let Kyle listen to it, and tell him about modern music, as well as show him pictures from topside. (I’m terrible with gift ideas, made harder by the whole rapture thing, but that’d make Kyle happy beyond words)
who remembers things?: Piers hasn’t been in Rapture as long, so his sense of time might be a lot better than Kyle’s. He’d remember what day it was, and holidays. Kyle would remember specific things about Piers, his birthday, things he likes, everything he’s told him about his life topside.
who cusses more?: Piers? Kyle rarely curses, he doesn’t like the way it sounds, but isn’t bothered when other people do it.
what would they do if the other one was hurt?: Kyle frets and coddles like crazy. A scratch could have him trying to wait on Piers hand and foot. So substantial damage could set Kyle into a panic. Not enough to render him unable to help, but it’d be quiet frantic and he’d worry until Piers was completely better.
who kissed who first?: Piers kissed Kyle.
who made the first move?: Piers did this too :l Kyle doesn’t make moves on other men….. Not purposefully, at least.
who started the relationship?: I guess Kyle made the final decision.