"Hefna" is Old Norse for "Avenge", and the title carries more than just the obvious significance! The background of Asgard and the Nine Realms that I'm using here is a combination of the original Norse Mythology and the Marvel canon. "Barnœska", the title of the first chapter, is Old Norse for "Childhood".
Frigga loved her two sons each as much as a mother possibly could – against all odds, in some respects. But despite this love, even she could see how Loki, the younger child, struggled to find his place in Asgard. The boy was quiet and tended to spend his time engrossed in library books, seeming to shy away from public scrutiny while his older brother, Thor, revelled in attention of almost any kind. She knew there were very sensible, valid reasons why the boys should be so different from each other, but that didn't make it any easier to accept. She's had her reservations when Odin had first brought the tiny baby, who would soon grow to be her Loki, to Asgard from Jotunheim, how could she not have? But in no time at all, he had come to occupy the same space in her heart as Thor did – and she was under no illusion that Odin hadn't expected for this to happen. She had always treated the boys equally, but as they approached their adolescence she had started to see their differences more and more often.
Thor was now almost never without his trio of friends – Fandral, Hogun and Volstagg – and in recent months she had noticed that the young Lady Sif had been spending more time with the rowdy boys. Thor constantly tried to include his little brother in their games, but on the occasions when his attempts were not futile Loki still did not appear to enjoy himself.
Frigga only ever really saw the boy come into his own when they left the royal hall of Gladsheim and ventured to the smaller, more private hall of Fensalir. There, away from the prying eyes of the court, she saw her sons acting as brothers should do, and as they had done when they were small. It was here that their differences complimented each other as they worked together, rather than set them apart. Where Thor was boisterous and loud, Loki was thoughtful and quiet – but when she saw them together at Fensalir she saw how protective Thor was, and how Loki seemed to be better than most at keeping Thor in line.
But no matter how much she saw them bond during these times, it didn't really last when they returned home. Thor would go back to his friends and their training, while Loki would go back to his books – or to practising spells in the Gardens of Ida, where he could escape from the scrutiny of his tutors. Though there was never any animosity between them, she longed to see their closeness return completely. Frigga could only hope that this distance would pass, and that Loki would begin to involve himself with the others once more . . . But she also couldn't help but wonder if her bookish boy now had too little in common with the young warriors for that to be possible. Loki was more interested in stories and spells than in swords and sparring. He excelled in spell-casting and magic while Thor and the others were sure to become Asgard's greatest warriors when they were older. These things did not, in her experience, need to be mutually exclusive, but there was only so much pushing children could stand and she was loathe to steer either child too much in any direction for fear of them going against her out of spite.
That being said, when the Lady Freyja visited Gladsheim with her youngest daughter Sigyn, and Frigga saw the book clasped tightly in the girl's hands – well, what other decision could a concerned mother make?