Melissa watched as the two mermaid sisters continued staring into each others' eyes. Their expressions changed, they were now looking at each other in a way Stefanie looked at Melissa before, and Emily was returning the gaze. Before Melissa could speak up about this, the two girls passionately moaned "Sister!" at the same time and wrapped their entire mouths around one another.
Melissa was shocked; this was hardly a kiss two sisters should be giving one another! Through the bond Melissa shared between the other two girls through their own individual kisses, Melissa could sense a new bond form between the two girls that mirrored their own with her. Melissa could feel their sisterly love inside her; and in her mind, she was now starting to identify herself as their sister, as well.
"S-Sisters!" Melissa moaned as she swam closer, and Emily and Stefanie invited their new sister into their circle to join in their passionate make-out. Three pairs of lips pressing together, three tongues wrestling around one another; Melissa came to realize that sisterly relationships among mermaids were different than with humans; that this was pure and right!
"You're my new big sister!" Stefanie said to Melissa.
"Welcome to the family, my dear sister!" Emily said.
"I feel it!" Melissa gasped; "I truly am your sister!"