Severus Snape was always a very practical person. He had a very good hold on his emotions. His face remained a stone wall ever since Lily Potter's death. No one had seen what happened when his facade cracked - except an unsuspecting group of third years.

Remus didn't plan on falling for Nymphadora Tonks. In fact, he tries to avoid the fact that he did. And he definitely didn't plan on leaving his notebook in plain sight, where Tonks might or might not be able to resist to urge to read it. Remus/Tonks