Well, in terms of characters, some are fictionalized. The real historical figures had more complex lives. For instance, Uhtred in the show has some fictional adventures added. In fact, the historical context was full of political intrigue that the show may simplify to keep the story flowing. The real events were spread out over a longer time and not as neatly packaged as in the fictional story.
The show may also exaggerate the role of some characters. There are minor characters in history that in the show are given more prominent storylines. This is done to add more depth and variety to the overall narrative. However, it means that the show is not always a completely accurate representation of historical events and the people involved in them.
Well, in terms of fact, archaeological evidence shows that Vikings had certain burial practices related to their beliefs in the afterlife including Valhalla. However, in 'Vikings Valhalla' (fiction), they might make up relationships between characters to add more drama. For example, they might create a fictional love story between two characters that has no basis in historical fact but serves to engage the audience more. Also, the show might over - emphasize the role of some individuals in Viking society compared to what historical research suggests.
The Last Kingdom is fiction. It's a historical fiction series. It takes place in a historical setting, but many of the characters and specific plotlines are made up for the story.
Yes, 'The Last Kingdom' is based on true stories. It is based on Bernard Cornwell's series of novels which are inspired by historical events and figures in the Anglo - Saxon period.
Mildrith is a character in The Last Kingdom novel. She has a complex relationship with the protagonist. She is often caught up in the political and social upheavals of the time in the story.