in gossip girl who is blair's baby daddy
Prince Louis
Season 5
 Blair tells Chuck that the child is Louis', 
Louis UNANSWERABLE Chuck Bass
Blair Waldorf Blair Waldorf
Season 5 Story lines
In the fifth-season premiere, Blair continues to plan her wedding, but begins to encounter problems in her relationship with Louis. It is later revealed that she is pregnant.  She later grows closer to Chuck Bass (which initially occurred in the series' television adaptation), who she'd previously known for years, which leads them to briefly date one another.
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Blair Waldorf [SEP] Season 5
In the fifth-season premiere, Blair continues to plan her wedding, but begins to encounter problems in her relationship with Louis. It is later revealed that she is pregnant. Blair tells Chuck that the child is Louis', and states that part of her wanted Chuck to be the father. Dan becomes Blair's confidante and is shown to be in love with her, though she remains oblivious to his feelings and states that there is nothing more than friendship between them. Though she insists that she is in love with Louis, Blair begins to seek Chuck out as the season progresses. The two eventually declare their love for each other prior to a car accident in her limousine while being chased by paparazzi.