looking at the tape
Join Date: Mar 2005
Location: The Book of Love
So yeah I'm going with the Earl's daughter is really Rollo's. The main problem is Rollo's age relative to Thyri's of course. He seems to be in his 30s and she in her teens. So it's possible he could've fucked Siggy when he was a teenager. There seems to be clear history between Siggy and Rollo. When Haraldson offers Thyri to Rollo, Siggy shows up and gives Rollo a knowing look. Rollo refused to marry Thyri by siding with Ragnar, but he also sided with Ragnar because he has the hots for Lagertha. Rollo shows up at Thyri's wedding. Why? He's risking death here since he betrayed Haraldson. Aside from him being stupid, which is totally possible, he could've done this to see his daughter be married.
Not saying this could be the case 100%, but things do fit. Maybe I'm reading too much into it. We shall see.