Notes at the bottom. Thanks for reading.
Only time can tell
Loki had always been a sickly child, always small and weak when compared to the other children of Asgard but Frigga loved him so dearly, it broke her heart when Loki came to her crying because the other children, including his brother Thor, had not let him play with them. She had had many stern words with Thor about including his brother in his games but it always came to naught. Eventually Loki gave up trying to join in the games of his brother and his friends, opting to avoid the inevitable teasing that would occur whenever he asked.
Loki was particularly down that day when he finally came to her. He was seven which was only four years behind his brother but the differences between them were astounding. Where Thor was loud and preferred physical pursuits, Loki was nearly always silent and liked to read more than any thing else. Also the physical differences between them were profound. Thor was tanned from the Asgardian sun and days spent playing beneath it, he was also tall and beginning to develop as a man. Loki, however was the exact opposite, he was pale from days spent alone indoors and was remarkably short and extremely thin for his age. He had always had problems with food, as a younger child he had become horribly ill and from that time on Loki barely ate, no matter how hard Frigga and Odin tried to encourage him.
When Loki quietly slid into her rooms, it was after the evening meal and she had not seen Loki since the morning meal. He hadn't come to the noon day meal or the evening meal and he also hadn't come to her when she had gone looking for him as he usually did. She had been beside herself with worry, Odin had just left to organize the guards into search parties for him, he had been missing so long and it was so unusual that he wouldn't show himself when they called. When she saw him, she ran to him scooping him up into her arms noting that he had recently been crying. She kissed him, "Oh my darling, I've been so worried, where have you been? Your father and I have been searching for you" she was beyond relieved. Loki didn't answer just buried his head in her hair, grasped at her dress and began to sob.
It was at this point that Odin returned, he saw his wife holding their son and relief washed over him. Loki was safe. He made eye contact with his wife and her gaze told him that she would handle this for now and that shouting at him for not coming to them sooner would only make things worse. So he did the only thing he could do, he informed the guard at the door to stop the search parties and to inform them that Prince Loki had been found. That done he walked to where Frigga and Loki stood and embraced them both, Loki held between both of his parents, who loved him with all their hearts.
When Loki's sobs had died down, Odin released his hold on his wife and son and directed them to one of the sofas in the room. He sat down with Frigga next to him and Loki sat on her knee, his head lent against her chest. His face was puffy and red from crying and his expression showed his emotions, he made a thoroughly heart breaking sight. "Tell us what happened today darling" Frigga prompted, wanting to find the problem that was causing her beloved son pain. "Said...too small...he...weak" the quiet voice of their son was filled with a sadness that no child should feel. "Who said?" Odin asked though he had a strong suspicion that it would be Thor and his friends once again that had brought Loki to tears. "...donmember" Was the only answer that they got, luckily they had both spent enough time consoling Loki that they knew what he meant. Odin just knew it was Thor "I know that you remember Loki, was it Thor and his friends again?" His suspicions were confirmed as his son nodded lightly in answer to his question. He really did need to do something about that boy, Thor was getting out of control, as heir apparent Thor was entitled to a lot of leeway with his behaviour but when had he decided that picking on his brother was acceptable behaviour.
Odin knew Loki wasn't at fault in this, he actively avoided Thor when he was with his friends. Loki had learnt quickly that the boy he loved as a brother changed when in the company of the other children and he had learnt to avoid them when he could. He would never have sought them out for himself. Odin sighed at the prospect of taking Thor in hand, it wouldn't be easy, he loved both his sons deeply but something had to change. He wouldn't force Thor to include Loki in his games with his friends but the name calling and the bullying had to stop. Hopefully when Odin put his foot down it would end and the boys would be happier for it, however there was also the possibility that Thor would blame Loki for his punishment which could increase the wedge that was between them. Only time would tell the consequences of his actions.
Frigga tightened her grip on her son, she too was thinking about what to do about the situation. She and Odin would have to discuss it later, it was such a tricky thing. How to protect the boy in her arms from the words of others. Words he may well hear all his life. He would never be physically strong like all the others and he would always have his pale skin and dark hair that set him apart from the rest of Asgard however he would also always have her love. Whatever he did and whatever he became she would always love him because he would always be her son.
She released her grip on the child in her lap as Odin pulled him from her, it was time for the now traditional 'teach Loki a trick because he likes them and they make him happy' part of Odin's role in consoling his son. Frigga watched as Odin sat Loki on his lap and began to teach him the hand movements and words of a spell to create butterflies out of nothing but air. Loki was becoming more and more adept at the magic that Odin was teaching him, she was glad Odin had taken it upon himself to tutor Loki in the arts, as she dreaded to think of the teasing and mockery that would fall on her son for studying, and being exceptional at, a skill that was considered a womanly gift. Loki would have to deal with that later but for now only Frigga and Odin knew of his skills in that area. For now she was happy with that and when he managed to create a rather impressive couple of butterflies after only a couple of tries at the spell she clapped and encouraged him because she was his mother and she would always be proud of him.
How could two children as different as Thor and Loki get on. Children are children. In this Thor is a growing child, he doesn't think about how what he does affects others, he only wants to play with his friends and when they tease his brother he goes along with it. He learns that they laugh when he's mean to Loki and just like Loki, Thor wants to fit in. The morning the story takes place Thor had probably taken the teasing further than he meant to. He still loves his brother of course but having friends is important to him as well. When Odin, and Frigga to a lesser extent, 'deal with him', is when he sees how he has treated Loki and becomes the protective brother of the film. Just trying to make some excuses for Thor and tie it back to the film.