Starprincechaser except it's James and Sirius competing for Severus and Severus could not care less.
Sirius is constantly walking him to class, giving unsolicited answers to tests and such (that are also probably wrong), handing him a jacket whenever it's cold out, etc.
James glares at Sirius while this happens, doing the same the next day (probably different favors), and every day, they meet up with each other and are both like, "hah! I'm his favorite now!"
Meanwhile Severus is so confused, probably staring at a wall, questioning all of his life choices.