The two of us can speak from direct experience: Barbara has an identical twin sister and Amanda has a fraternal twin brother, and we’ve both spent much of our lives fielding questions about what it’s like to share a life with someone you once shared a womb with.
Ivan makes me so happy, he's always there for me.
I'm so grateful for Ivan, I honestly think he is the best person to ever walk into my life. We had talked every other day on Face Time and Snapchat, text each other but we still missed having great laughs together.
It goes without saying that most Real Life twins are as completely repulsed by the idea as any other incest trope. If it's just implied, then it overlaps with Incest Subtext.
It's also important not to make mistakes with other Brother Sister Incest couples, since, due to the popularity of this trope and the idea of a spiritual bond of twins, many "ordinary" couples between brother and sister can imitate many twincest cliché elements.
They can overlap if the twins are interested in both each other the third party, but that's rarer.
If the twins have a child together, that may be known as twinbreeding.
What was it like being away from your best friend for eight months? I'm so glad I got to make more great memories with her, she's the best friend I could ever ask for. Gabby~ Ally and I became best friends in high school, we had history class together.
We didn't know each other at the time but then my friend and I walked into the councilor's office and Ally was trying to decide what elect to change to Drama or Art and my friend at the time told Ally to change to Drama.
It's especially common as a way of making Creepy Twins just that much more disturbing, often as a form of Villainous Incest.