17+18=69(?)

Shortly later 17 was on his back as 18 rode his face and tongue to yet another orgasm. He had given her 2 orgasms in just a few minutes and he wasn't finished yet. 17 knew his sister well enough to know that by now her pussy and clit would be extra sensative so he quickly took her clit into his mouth and started to bite down on it, nibbling and teasing it with his teeth.
18 arched her back and cried out as 17 bit down on her she squirmed on his face riding him like crazy as his tongue on her pussy sent waves of pleasure through her body. 18 liked it a bit rough on her pussy and her brothers biting her clit was was wonderfull. 17 still had more planned for her though and he brought both of his hands up, one of his hands he moved to her pussy and immediately shoved two fingers into her sliding them roughly back and forth inside of her, the other hand he brought to her ass and there he also shoved two fingers into her ass hole. There was no lubrication on her ass so the fingers he shoved into her slid in with a lot of friction.
18 loved it when her brother shoved fis fingers into her pussy and ass at the same time, the feeling of being filled was almost overwelming and the intense friction in her ass was like an electric jolt running through her entire body. 18 realised the only hole of hers left unfilled was her mouth and she quickly decided to remedy that. He has done a good job, I suppose he has earned a reward. 18 thought to herself. Since her brother was also now nude 18 leaned forward and took his cock into her mouth. Descending slowly she took only an inch at a time, pulling back and then plunging down again until she felt his cock hit the back of her mouth. Relaxing her throat she pressed further and her brother's cock slid into her throat all the way to his base. The two of them laid on the ground in the classic 69 position with 17 on bottom and 18 on top, both sucking eagerly on the other.
17 had paused when 18 took him into her throat but quickly took 18's clit back into his mouth and continued to suck and nibble on her as his dick plunged repeatedly into her throat. His fingers continued to pump into her pussy and ass at super human speed though , he still wanted this to be the best sex she ever had.
18 loved the taste and feel of 17's cock and though she would never admit it to him he was the best she ever had. Still, no sense wasting this opportunity though. She thought to herself, knowing she had 17 willing to do anything she wanted. She moved her tongue over his cock as deep throated him she knew that he liked the sound of a wet blowjob as well , that the sucking sounds turned him on and made it better for him. Soon they were both ready to cum and through long experience with fucking each other they knew how to time it so they came together. 17 pulled on 18's clit with his teeth stretching it out while he twisted his fingers inside of her pussy and ass. 18 plunged her mouth fully onto 17's dick while reaching a hand out to gently squeeze his balls. WEith muffled cries from both of them they flooded each other with cum. 17's cumflowed straight into 18's mouth where she had pulled back enough to let it land on her tongue so she could taste it then swallow it. 18's cum flowed over 17's hand and into his mouth, where he eagerly lapped it all up.
When they had finished cumming they moved beside each other, 17 ran a hand over 18's thigh and looked at her asking "Well, have I proved my point yet? No one can do to you what I just did."
18 looked at him mischeviously and said.
"Well I'll admit that was a good start ,but it wasn't enough. I have something else in mind now if you really want to prove once and for all that I don't need anyone else."