Klaus saw Stefan sitting next to you. Klaus smiles at Stefan and Stefan smiles back. This is the point where you should give them privacy but who cares.

Klaus: Isn't it my old friend Stefan Salvatore. Nice to see you again.

Stefan: It been awhile yes but why are you here? He says with annoyed tone.

Klaus: Well just to talk about how I might kill your ex girlfriend Elena.

You were watching them and you kinda see some chemistry.

Klaus: I can't give you anymore freebies Stefan.