How serious should these two teenage characters get?

Hi guys! Im writing a story about vampires but not the type with sparkly vampires (ick!) but there are two teenage characters Celeste Chalet and Chase DiMarco and im just wondering how hot it should get between these two? So thnx fo ur help X) and p.s there is a bad clan of vamps and a good clan... Im kinda stuck on names so also if u could help with that! THNX!!