Unmarked (Waterman #1.3)
Dusk Peterson

In his final terms of school before his university years, Meredith is faced with a host of problems: A prefect who abuses his power. A games captain who is supposed to protect Meredith but has befriended the prefect. And a legal status that makes everyone in the school question whether Meredith belongs there, among the elite.
Unexpectedly, rescue arrives, in the shape of a fellow student who seems determined to right wrongs. There's only one problem. . . .
"Fair play" is the motto of the Third House, but that motto takes on a different meaning when Meredith is secretly wooed by a young man from a rival House.
This novel can be read on its own or as the third and final story in the "Master and Servant" volume of Waterman, a historical fantasy series and retrofuture series inspired by the Chesapeake Bay oyster wars, boarding school rivalries in the 1910s, and 1960s visions of things to come.