the first kiss: sherlock realized that molly’s feelings are real and strong. molly was surprised, she didn’t expect for that kiss. the first significant body contact between them. simple, beautiful and
spontaneous. sherlock wanted to apologize for being an idiot with her, and finally accepted that her feelings are real, and he should not play with them.
the second kiss: molly didn’t expect for that kiss either, but she smiled. she was happy because sherlock was back, and because he seemed to care about her. sherlock knew molly was engaged, but he still kissed her anyway, like he needed to do that. it was important to him.