You decided that it would be best if you didn't use a condom, Sydney reluctantly says fine.
You begin to have anal sex, Sydney moans in pleasure saying "more, more, go harder." You proceed to go harder, as she exclaims " I'm the happiest half cephalopod woman alive. Some time later you proceed to put your parts together and then while you're having fun, you begin to shrink without knowing it. Sydney then moans "veemo". Your hair grows longer and suckers form on top of your head and your hips widen and breasts form on your chest. Right before the session ends your dick shrinks and goes into your pelvis area, a vagina in its place.
Sydney acting confused asks you why you decided to stop, and then shrieks in horror and surprise. Turns out your skin still feels human, your pupils are still human as well, and then you feel your hair, it's silky but still hairy. Sydney then realized what happened and states, "so it seems that when we had sex, you began to transform, but like some bonkers STD, you somehow are half cephalopod and immune despite your gender change.
The next morning you wake up and sit by Sydney at the pond, Sydney mentions that when scavenging yesterday she found a map that someone left behind in a hurry, and that it leads to a lab, she says "we have a choice, we could go to this lab and possibly make a cure, or we could build a life here at the shelter." She then asks you "what choice do you choose?"
Note: your immunity gained by stupidly not using a condom, gives you access to some choices you didn't have before and prevents some bad endings.