Sebastian and ominis have been both dating Liliah for over 2 years as both Sebastian and Ominis took Liliah together to the Yule ball dance

Sebastian and Ominis both drinks and come back to see their beautiful girlfriend Liliah looking uncomfortable with Garreth as Garreth is forcing Liliah to dance with him

Sebastian: Garreth f*cking Weasley! Stop forcing our girlfriend to dance with you

Ominis: yeah Garreth! She's taken by us