"But Jooohn," Sherlock pouted, trying to give John the puppy dogs eyes. It didn't seem to be working, though, so he reverted to a grumpy pout. Soon John would regret allowing Molly onto their boat. His and John's! Not hers. 
Molly stepped onto the boat carefully, smiling warmly at John. "Molly Hooper," she shook his hand. "It is nice to meet you as well." She sat down, tilting her head and looking at John with deep brown eyes. "How did you meet Sherlock?" She looked genuinely curious. She had expected to find Sherlock in a boat on his own. He'd never really gotten on with people. Molly adored him, she really did, but he had always brushed her off. It hurt but she kept trying. She understood that he just wasn't a good people person.
Sherlock had brought his knees up to his chest, looking out at the water and now in quite a royal huff. He didn't like Molly monopolising John's time.

(That's a really good idea! I need to start thinking some up xD You keep coming up with them all... And I think some kind of dog might be cool - and golden retrievers are known for being loyal I think :3 Sherlock's will probably be a fox, or maybe an otter)