Oliver's team had just lost to your house in quidditch, and to him, quidditch was more important than oxygen.

The moment he found out he had lost, he headed straight towards the broomshed alone, trying to compose himself from the disappointment.

That's where he found you, the prefect from the winning house, after seemingly congratulating the quidditch team.

He roughly puts his broom down, not caring about your presence, you are enemy at that minute. "Go celebrate with everyone else, please leave the shed." He scrambles through his gears in annoyance.

An Oliver Wood enemies to lovers story; prefect & the quidditch captain