Ragnar arrives in Hedeby where he is greeted by Astrid who remarks that her wet nurse told her many stories about him. While there, he apologizes to Lagertha after she refuses to accompany him to England. Ragnar departs, though Lagertha and Astrid proceed to have passionate “steamy” sex before later arriving in Kattegat. Lagertha wishes to see Björn, who has decided to send messengers to Rollo in England.
With Ragnar, three of his sons and many others away sailing to England, Lagertha plots her revenge. Astrid lures Ragnar's remaining sons Sigurd and Ubbe into a trap and threatens to kill them both after Ubbe fails to attack Lagertha's guards. In the end, Lagertha is successful in reclaiming Kattegat, killing Aslaug in the process and securing herself and queen.
Elsewhere, Ragnar meets his end and the news slowly makes its way back to Lagertha. Astrid consoles her lover after the death of her former husband. When Björn returns home, he and Astrid become lovers, perhaps to spite Lagertha (Astrid was upset that she does not fully reveal her plans while Björn is tired of being told what to do).
Later, Egil attacks Kattegat on Harald's orders; Lagertha, Astrid, and Torvi. among many others, repel the attack. Astrid strikes Egil down, though Lagertha prevents her from killing him - she tortures him later for information.
Astrid is kidnapped by Harald and his fealty and is taken to his kingdom, where she is forced to marry Harald by which she becomes Queen of Vestfold and Rogaland. She is later gang-raped and tells Harald, shortly after, that she is pregnant, however, it is unconfirmed if the child was a product of Harald or the assault. She and her unborn baby are later killed at the hands of her former lover, Lagertha because Astrid didn't want an other life than with a warrior with Lagertha, and supplied her only true love to kill her.
Astrid is a strong shield maiden, who's inspired by Lagertha. She's intelligent and gives the impression of being loyal to her Queen. Astrid has shown to be slightly envious of Torvi as she as Lagertha's counselor.
|Season four appearances|
|A Good Treason||Kill the Queen||Mercy||Yol||Promised|
|What Might Have Been||The Profit and the Loss||Portage||Death All 'Round||The Last Ship|
|The Outsider||The Vision||Two Journeys||In the Uncertain Hour Before the Morning||All His Angels|
|Crossings||The Great Army||Revenge||On the Eve||The Reckoning|
|Season five appearances|
|The Departed Part 1||The Departed Part 2||Homeland||The Plan||The Prisoner|
|The Message||Full Moon||The Joke||A Simple Story||Moments of Vision|
|The Revelation||Murder Most Foul||A New God||The Lost Moment||Hell|
|The Buddha||The Most Terrible Thing||Baldur||What Happens in the Cave||Ragnarok|