When the Earl raids the Lodbrok farm, the Lodbrok family grabs daggers and axes and swords. Athelstan grabs his bible; his weapon is the Word of God. The heartwarming continues when Lagertha nonetheless hands him an axe despite being a slave.
Bjorn refusing to leave his father alone to Haraldson's warriors. And Ragnar's insistence that he leave with his mother and sister and get to safety.
The Lodbrok family arrive at Floki's home and Bjorn says his father is dying. Immediately all the silliness goes out of him and focuses 100 percent on treating Ragnar's injuries.
There's also this conversation from the same instance;
Floki: You are alive. Ragnar is alive. Your children are alive. You have everything left.
Lagertha: We're eating your winter supplies, Floki. I am ashamed...
Floki: *shakes head* The gods will provide.
Haraldson saved two locks of hair from his sons' heads and kept them as a keepsake since their deaths. He later gives them to his wife. Even Evil Has Loved Ones, indeed.
Athelstan asks questions about the Norse religion like a fascinated schoolboy. Despite being a priest, he doesn't look down on the vikings for their paganism and instead shows them a great deal of respect.
Athelstan jumping into a river and saving Ragnar's life. And later, praying over his body.
"Mary, Mother of God, listen to me... Do not let this man die..."
The moment between Ragnar and Lagertha when the latter tells him that she's pregnant.
Ragnar: I know you're a boy. The Seer told me. By all the gods, my son, you've made me a happy man.
Lagertha taking Siggy and her daughter under her protection when she asks to serve her, and then telling her she will never treat her as a servant. This is the wife of the man who nearly killed her whole family, by the way.
When Tostig is felled from behind (after killing several Saxons at once, to reiterate), Ragnar rushes from one end of the battlefield to the other to help him and kill the Saxon coward who struck him in the back. After dispatching him, Ragnar kneels beside Tostig; Travis Fimmel's look of sheer distraught is heartwrenching enough on its own, and shows the sheer depth of the friendship between the two characters. Tostig's contented smile that he will finally enter Valhalla is the only thing that lifts some of the pain of his passing from Ragnar. And it is also a great performance by his actor, as well. All in all, it's a beautiful scene.
Leif helping Athelstan up in episode eight. Also the resulting exchange, it shows how far the Vikings have come to accept him as a fellow.
Leif: Surely you're not tired, Athelstan? On this great journey you've begun and must finish. *helps him up*
Athelstan: Leif, if you let me go... I'll fall down again.
Leif: No... You won't. The gods shall hold you up.
Leif lets go of him, and despite being stoned the fuck out of his mind, he does remain standing. Leif's belief once again reiterates the respect he has for Athelstan. It makes his later volunteering for the sacrifice all the more emotional.
Similarly, in Burial of the Dead, Athelstan is being his curious self. Floki will have none of it, of course, but rather than mocking him as has happened before, Floki chides Athelstan and hands him dinner.
"Just eat your soup, priest."
Ragnar denying Aslaug's advances for the sake of his son.
When Gyda and Athelstan are ill, Gyda asks her mother to make a sacrifice for Athelstan. He survives. She doesn't.
When Athelstan wakes from his illness, the very first thing he does is scramble up and crawl over to Gyda's pallet. Only to find her dead.
Ragnar bribing the Law-Giver to spare Rollo's life, even after his brother had taken up arms against him.
When Ragnar drops the blanket over the child at Winchester to hide him from the others, there's a beautiful half-second shot of the child's smile before it falls over his head.
Ragnar and Bjorn's reunion.
Lagertha showing nothing but respect to Aslaug, despite having every reason to loathe her.
The reactions of Ragnar and Bjorn to Athelstan's supposed death. And then, when Horik and Floki both call him a worthless individual and traitor, Bjorn doesn't hesitate to defend the priest's honor. There's no doubt after this that Athelstan was very much loved and cared for by Ragnar and his family.
Bjorn: Poor Athelstan... My sister and I grew to love him when we were children.
In a bizarre sort of way, it is heartwarming to see Jarl Borg carry his wife's skull to his execution, hammering home just how much he valued his lost bride. He has been stripped of his title, men, power and most of his clothes, but he will not depart from this world without his beloved wife by his side.
Aslaug refusing to let her deformed son Ivar be killed or left to die in the woods.
The absolute happiness and excitement on Ragnar's, Lagertha's, and Bjorn's faces when they're given Athelstan's arm ring and Aethelwulf offers to use him in a hostage exchange, which confirms the Seer's words and proves that Athelstan is alive. Extra points for Ragnar immediately grabbing the arm ring, checking its design and then putting it on his own arm, so that he can keep caressing it. Awwwwwwwww.....
Torstein wishing Rollo a safe journey in Episode 6. After what Rollo did, Torstein was the one who hated him the most, and his approval is proof that Rollo has redeemed himself.
Torstein: "I, too, wish you well." Rollo: "Those words mean a lot coming from you." Torstein: "They were hard to say. Now they are said."
Ragnar is very proud of what a great warrior Bjorn has become and he even nicknames Bjorn "Ironside".
Aslaug sparing her son Ivar, who was born a freak, when everyone (including her husband, the child's father) wanted her to kill him. For the first time the most hated character in the series does something truly selfless.
The entire reunion between Athelstan and the Vikings in The Choice.
Although it may come across as slightly morbid to those unfamiliar with the show, Bjorn's response to Athelstan's arrival is downright sweet. At least by his standards. And despite being much older than last time he'd seen him, Athelstan instantly recognizes Bjorn from the rest of the Vikings.
Athelstan: Hello, Bjorn. Do you remember me?
Bjorn: Of course, I remember you. I wanted to kill you when I was a child. And then I loved you.
When Athelstan prepares to return to Ecbert's castle, Ragnar offers to escort him part of the way and casually wraps his arm around Athelstan's shoulders, effectively using himself as a human shield against Horik's archer in the nearby woods. It's made very clear that Ragnar knows about the archer and his intentions, but doesn't care about putting his own life at risk to protect Athelstan.
Ragnar's easy acceptance of Athelstan's torn and confused loyalties between the Norse gods and Christianity. He doesn't pressure him to convert, but instead offers words of compassion to Athelstan's religious plight.
Ragnar: I hope that someday our Gods can become friends.
After escorting Athelstan to safety and then returning his arm ring, Ragnar promises to see him again very soon. Less than a day later, Ragnar, Lagertha, and Bjorn arrive for peace negotiations at Ecbert's castle with a very petulant-looking Horik in tow. And then, after the negotiations are finished and the Vikings are about to return home, Ragnar begs Athelstan to return with them.
Ragnar: Will you come back with us or will you stay here with...your people? I want you to come back.
When Athelstan is sailing back to Kattegut as a free man, he looks genuinely, uncomplicatedly, happy, for maybe the first time in the series.
His simple reasoning for returning to Kattegut.
Athelstan: I came back because you and Ragnar, all of you, are my family.
Ragnar's relief when he finds out that Rollo survived the battle.
Aslaug giving Thorunn her freedom and a dress. Sure, it was more likely than not an attempt to get in Bjorn's good graces, with Aslaug practically presenting "free Thorunn" to him like a shiny new toy, but the moment of freeing her is nevertheless heart-warming, because Thorunn never even considered the possibility that she might be truly free one day.
The waterfall scene of Ragnar and Athelstan praying together.
Ragnar: I see you praying to your God. Will you teach me one of your prayers? So I can learn?