My question is; What is the impact on the surviving twin, if one twin dies as a baby? I am writing a novel with one of the themes as repressed grief (parental) but wonder if, as a teenager, the ssurviving twin has any feeling of loss for a twin she/he never knew. All answers greatly appreciated.

If you want to implement a psychic or psychological element to the story,you could have the survivor be protected by the spirit of the other.Keeping her out of harms way by telling her which action to take.

Or,it could be darker and the deceased twin has evil motives and impels the survivor to do negative things.

Or you could make it appear that the lost twin has evil intentions toward the survivor but in fact the outcome is positive.

The character could not know that he/she was a twin and always have a feeling of being half of a whole.

Just throwing some things out there :)

You have a great question. I am 15 years old, and I lost my twin brother one week before we were due. The death of my brother was never truly known, which maks me uneasy as well. It is true,that I do sometimes feel half a whole, and I wonder why I survived while my brother died. It has had a great impact on me throughout my life, and sometimes it does feel like I have a guardian angel, or someone around me at all times.