"I care" is an expression of affection and/or appreciation, mixed with just a hint of longing. Sometimes intended to have slightly inappropriate or icky undertones.
Poster #1: "I'd post my big drama-filled life story about the terrible things in my life, but nobody would care."
Poster #2: "I care."
Star Wars, n00b!
Specifically, a creepily incestuous comment Luke Skywalker offers as his sister, Princess Leia, storms off in a huff after getting angsty at Han Solo. Luke wants Leia to know that even if Han treats her bad, he'll be there for her. All night long.