"Deepthroat me"

Feeling both eager to cum, and to get back at Fiona a little, you take a seat on the couch, point at the floor where you were just kneeling, and give Fiona an order. "Deepthroat me."

Fiona grins, passing you your phone before taking up her spot with surprising obedience. "Left you some fap material there as a gift. No need to thank me."

You expect a saved clip of Allison's cam show, but find a short conversation instead. You guess that this is what Fiona was up to once she had you jerking her off...

The contents immediately leave you wanting to ask Fiona what is going on, but seeing you open your mouth to speak, she leans forwards and wraps her lips around your cock. You pause to let out a groan, and Fiona's eyes seem to mock you as she slowly begins taking more of your dick into her mouth.

You're torn between enjoying your smoking hot sister slowly slide your lips down the length of your cock...and reading the somewhat alarming conversation between Allison and "you"(Fiona) saved on your phone.

he wants me to suck his dick...not sure about it though

wow! thats kinky...nop ressure, but thinkng about thats getting me really hot!

Allison's still making typos, and evidently stopped to show off a bit after her message.

wow, that was hot...um...okay ill do it

youre thebest! love you!

As you read, you feel Fiona's lips reach the base of your cock. With far less trouble than you'd expected, she's taken your whole length into her mouth...though, she's probably sucked your mother's behemoth at least once, so it's not that surprising. In any case, the tip feels very nice in her tight throat. She's barely moving though, perhaps to give you time to read before she makes you cum.
__

When the messages resume, it's one-sided from your phone.

hey slut. your boyfriend's busy **** on cock, so im using his phone

haha, that get you horny? gonna cum all over him and send you a picture, so give me some more of a show

There's a time gap again, before you see a sent image; it's from Fiona's perspective and shows you on your knees, plastered in cum and sucking on the tip of a huge dick. The image doesn't show the rest of Fiona, so to anyone looking at it, you seem to be sucking a man's cock...your flushed face and visibly erect cock make it seem (perhaps not incorrectly) like you're enjoying it too.

Fiona seems to realize based on your expression that you've reached the picture, as she abruptly twirls her tongue around the underside of your cock and begins bobbing her head up and down with enthusiasm. You groan out loud, unable to help it...Fiona's warm mouth feels amazing.

With the picture on your phone, you can't help but notice the contrast between it and the sight in front of you. Fiona looks clear-headed and confident, easily engulfing your entire cock with her mouth as she sucks you off.

Meanwhile, your face in the photo looks dazed and overwhelmed, with only the very tip of the cock in front of you inside your mouth. Though you know you had other reasons to be horny, and were only cleaning Fiona up a bit, you can't help but see the image for what it looks like; you on your knees, worshiping a cock that's way too big for you.

Fiona sucks harder, and you dig your fingers into the couch as your cum is practically pulled out of your aching cock. Though you try to focus on the incredibly sexy sight of Fiona blowing you, your attention is divided between that and the image of you sucking Fiona off...even as you empty your balls directly down Fiona's throat, you can't help but wonder how it'd feel to blow her for real.