Tobias/Four: He wasn't a big fan on PDA. He would rather wait until you two were alone to show you affection.
Eric: He was a big fan on PDA. He didn't care who was watching. He would kiss you in front of everyone if he wanted too and not care. It usually left you blushing.
Peter: Like Eric he was a fan of PDA. He loved showing you off. He would at random times kiss you and show you affecton. He didn't care who was watching.
Caleb: He didn't like PDA. That's his inner Abnegaton. He usually loves waiting until you two were alone to kiss you.