When the news of Sigyn's second pregnancy had been formally announced, Narvi had been ecstatic. To have someone other than his mother and the servants to keep him company was all that he had wished for. He was a lonely child; there were few children on Vanirheim who wanted to play with the son of the Loki, intimidated, no doubt by the stories of his father. However, he lived for the moments he shared with his father. Loki indulged him with tales of the other realms, regaled him with grandiose demonstrations of magic, and taught him the importance of being astute. Still it wasn't enough to gratify his yearning for friendship. There were times when he ached to share his childhood joys with another. His mother tried to entertain him when she could as well but it wasn't the same.
Vali emerged from the womb on a cold, clear winter morning. Loki retreated from the birthing room to the hallway where his firstborn sat, cross-legged, patiently by the door. He sat down on the floor next to him in much the same fashion. For a long moment they were silent, staring down the dark marble wall across from them and just as Narvi was beginning to grow anxious his father spoke.
"You have a younger brother now." He said quietly. He shifted uneasily then turned to look at his son, who gazed up at him attentively. "Listen to me, Narvi…" Loki hesitated, careful to choose the right words, "You must be more responsible from now on. I cannot be here each day to look after him, to protect him and your mother cannot carry the burden alone. I need you to be his guardian for me... I can't very well concentrate on my duties in Asgard if I'm constantly worried about the two of you, now can I?" Narvi shook his head.
"Can I trust you to do this? Will you be a good older brother?"
Narvi nodded vigorously, "Yes, father! I'll be the best brother ever, I promise!"
Loki offered him a small smile, wrapping an arm around his thin shoulders and pulling him against his side. "Good." His voice was thin with exhaustion. "He will need you, he'll turn to you for advice and friendship…You must look after him diligently." Satisfied with the conversation, he kissed the top of Narvi's head, ruffled his hair gently and stood, pulling the boy up with him. "Now go see your mother." Loki pushed him towards the door.
Grinning, stomach fluttering with anticipation, Narvi entered the room and immediately made a beeline for his mother's bedside. He repeated the vow he had just made to his father, to which Sigyn responded with the fondest of smiles. "I do not doubt it, my son." Her face was drawn, pale, her golden hair a sweaty, tangled mess but despite her heavy fatigue her eyes were bright and lively. Sigyn gingerly passed him the carefully wrapped bundle and pink and plump as Vali was, cradled in his brother's small arms he was the greatest treasure to grace the nine realms.
Author's Notes:
Thank you for stopping in and taking the time to read this little drabble.
I might continue this; make it into a series of ficlets about the aesir sons of Loki with fluffy, brotherly love, magic and the bastardization of Norse mythology and all that good stuff.
A part of Loki's resentment towards Thor seems to be the fact that, despite there not being an obvious age difference, Thor is portrayed as the cool older brother and Loki as the annoying little brat. I believe Loki would have looked up to him, admired him as much he envied him. He really wanted Thor to have his back, to protect him against bullies even if they were Thor's friends, play with him without making him feel inferior, listen to him, include him, love him and support his interests. Although Thor is generally good-natured and isn't intentionally malicious, he always disappointed Loki and rejected him, albeit unknowingly. He never stood up for him, he never saw that Loki was unhappy and never sought to understand him until it was too late.
I think Loki would be afraid of history repeating itself when it came to his own children. He'd want to make sure Narvi was going to be good to Vali and take care of him the way he always wanted Thor to but never did. According to my headcannon, anyway.