Viking’s Contract Bride

The Viking clans put out a woman who has a child by a man she is not married to, and lords like Harald hold fortresses with whole households working inside them. Astrid is born into one of the noble families. Sigrid wants Harald for herself, so she puts a drug in his cup and in Astrid's, and the two of them spend a night together that neither intended. Astrid is pregnant afterwards. Her clan sends her away, and she raises the boy alone for seven years with very little money. Work at Harald's fortress is what she finds in the end. The household there goes at her constantly, so she and Harald sign a contract for an engagement that neither of them means, which gives her some standing. Sigrid keeps setting traps and feeding Harald the wrong version of them until he believes it and cancels the contract. What comes out after that is that Astrid and Harald were exchanged as babies and the rightful heir of her clan is Astrid. A blood test is held in front of the clan.