Chuck is a very likely candidate as he has a long - standing and complicated relationship with Blair in the Gossip Girl series. In many fanfictions, their relationship often leads to such a situation, and the drama of them dealing with a pregnancy together is a popular plot.
It could be Dan. Since they had a long - standing relationship in the show, it's not a stretch to imagine that they had a moment that led to Serena getting pregnant. Their relationship was always full of drama and passion, so this would add another layer to their story.
Chuck Bass could be a likely candidate as they have a long and complicated relationship in the show. Their on - again, off - again dynamic would add a lot of drama to the story if he were the father.
One possible storyline could be Blair dealing with the pregnancy while trying to keep it a secret from her high - society friends and family. She might struggle with how it will affect her image and future plans.
In some fanfictions, Blair's pregnancy could lead to her re - evaluating her relationships. Maybe she realizes that she has been too focused on the wrong things and starts to build stronger bonds with her family. It could also be a journey of self - discovery for her as she prepares to become a mother. She might start taking on more mature responsibilities and change her party - girl ways.
Serena is often a popular character in these fanfictions. She might be Blair's maid of honor and get involved in all the pre - wedding drama. Nate could also be a prominent figure, perhaps as Chuck's best man, and his relationship with other characters can add more depth to the story.
Another possibility is that the father could be a new character introduced in the fanfiction. This new character could be a powerful lord from a far - off land who comes to Winterfell, falls in love with Sansa, and they have a relationship. Or perhaps it's a mysterious figure with magical powers who impregnates Sansa as part of a grander scheme in the magical and political landscape of Westeros.
One great fanfiction could be 'Chuck and Blair's New Beginning'. In it, they face the challenges of pregnancy with their usual charm and tenacity. It shows how they grow together and prepare for parenthood, all while dealing with the Upper East Side drama.
Many fanfictions explore their relationship by putting them in new situations. When Blair is pregnant, they might have to deal with public scrutiny. This forces them to communicate better and support each other. Their love, which was often tumultuous in the show, becomes more stable as they face this new chapter together. They start to understand each other's fears and hopes more clearly, like how Chuck may be afraid of being like his father but Blair gives him the confidence to be a better man.
In one scenario, Nick could be the father. Given their on - again, off - again relationship, it would make for a really interesting story arc. Their relationship would be put to the test as they prepare to become parents. Another possibility could be Schmidt. Maybe there was a wild party night where things got a bit out of hand and he could be the father, which would create a whole lot of drama considering his relationship with Cece.
Blair could also be a character who is made pregnant in fanfiction. This could lead to a whole new set of storylines, like how she would balance her ambition with impending motherhood and how it would affect her relationship with Chuck.