Your comment on the "ship your OC with the person above you's OC" came as I was reworking Pierre XD He was pretty bare bones as far as a bio goes, his entire story revolved around a friends character that she never ended up making so I made my boy not need her(over a year is a long enough wait pfft)

But yeah that would be interesting for sure. I could see Pierre being called onto the nightingale case(or Frederick on his case) and working together its kind of tense. Pierre is the social buttefly, and gets snapped at by Frederick alot(like you said pffft). In the end Pierre figures it out, and in a dramatic standstill Frederick somehow figured out Pierre is also a killer. "You're a killer" "so are you." So they're both real tense but instead of killing each other they end up agreeing to both pretend like they're innocent. They're still on the case and somehow they get real close??? I could imagine maybe one day Pierre is blabbering on about something and Frederick is annoyed but snapping at him doesn't do anything so he just kind of kisses him and is like "You really don't know how to shut up". And that shuts him up and Frederick now has a tool to make him shut up.

Another little scene I imagined was like, them taking their gloves off for sleep, and since they're both black gloves Pierre swaps them just to be a goof. Later he takes them off and??? Gun??? Confusion occurs while Frederick probably flips his lid.

Also I could see Pierre saying sweet things in French to him all the time