Emily wanted to squeal. Would have too if she didn’t have her mouth full. In the end she just moaned vocally while momentarily holding Scarlett’s cock in-between her teeth. It sounded a bit like a grunt, quite honestly. The teeth thing was a good find though. She was gentle with them, but she could run them up and down Scarlett’s cock and they’d give quite the sensation to her sister as she ran them back and forth up and down over her cock-head where it met the shaft. She dearly wanted to chomp down hard on it but she knew that was mean - and besides, Scarlett would only go and do it to her right away if she did anyway.<br/><br/>Scarlett was sucking on Emily’s cock and Emily thought that it felt so wonderful she would have to return the favour. This whole experience was about them finding out what worked and what didn’t. They would notch this general topic down into the ‘works wonderfully’ column, of course, and they were really just seeking out little bits and things that made it work even better.<br/><br/>Scarlett was taking more of Emily into her mouth than she was. She couldn’t have that, either. She pushed forward so more of the cock slid into her mouth. Further, further…. She reached perhaps about three-quarters of the way down the shaft before it became too painful to do any more. She felt like she was choking on it and so she backed off. Some things, it seemed, needed a bit of practice to get perfect. Not to worry. She continued with the sucking and the tongue curling. For now that was going to have to satisfy Scarlett.<br/><br/>Hands…. So far they weren’t using them. Scarlett was still getting far more of Emily’s cock in her mouth than Emily was able to. Em wasn’t going to push things though so she tried something else to see if her sister liked it. Wrapping just her thumb and forefinger around the base of Scarlett’s cock, she squeezed it and began to slide up and down the shaft on the parts she couldn’t get in her mouth. She was half sucking, half jerking off Scarlett. IN HER MOUTH!!! After a few more suck-jerks she leaned back and let the massive - OK, yeah, it was fucking massive! - donger pop free from her mouth while she got her breath back. It was covered in her spit, and really slippery and shiny.<br/><br/>“Fuck sis, that is one tasty cock!” She looked down her body (up Scarlett’s) to see Scarlett still bobbing up and down on her cock and sucking furiously. She’d have to get back to doing the same or else she’d cum and Scarlett would be nowhere. She slid the cock back into her mouth and started to suck furiously at the same time as using her teeth the slide up and down on it. Maybe that would get her back in the game. For herself she could feel the familiar tingle in her cock as she got ever closer to an ejaculation. They hand’t spoken of whether they’d swallow each other when they came. Emily would swallow Scarlett’s for sure, but she didn’t know what her sister would do. It was a bit too late to find out now though wasn’t it?