While there isn't a single official link to watch The Vampire Diaries

If you prefer to own the season permanently without worrying about changing streaming catalogs, you can purchase individual episodes or the complete Season 1 on digital storefronts: Apple TV / iTunes Google Play Movies & TV Vudu / Fandango at Home The Risks of Using "Free Streaming Link" Websites

These sites often use aggressive scripts that automatically download spyware, ransomware, or adware onto your computer or mobile device.