Not a chance

Arya's smooth hand gently strokes your cock, easily gripping it and taking full control over where it's aimed. Meanwhile, the behemoth between her legs pulses and twitches as you stroke it with both hands, feeling like a wild beast on the verge of escaping your grip at any moment.

The sheer contrast cock size excites you for reasons you can't adequately explain...and the fact that it's your own sister's cock that's completely emasculating you only adds a forbidden charm to the whole thing.

Just experiencing so directly how pitifully under-equipped you are compared to Arya has you too excited to think straight, and with only a few moments her soft hand stroking your cock, you let out a little groan and cum explosively, semen splattering all over Arya's hand, arm and lower body, including her still throbbing cock. You don't even have time for a warning before you let loose, prompting Arya to let out a little yelp of surprise as you make a sticky mess all over.

Your knees buckle as the intensity of your orgasm fades, and you release Arya over-sized cock as you fall on your ass, your sister reaching out her non-sticky hand a moment too late to catch you. Luckily, you aren't really hurt, but how does Arya react to your unexpected lack of 'stamina'?