I'm looking for a novel where the main character is a super-soldier called Lambda 602 who's just like Master Chief from Halo.
He is transported to fantasy world, where he became a familiar their that he believes that its his commander
This is the web-novel 'Blessed are the Simple' by naturalpinkflamingo.
Blessed are the Simple tells the story of Lambda Six-Oh-Two, a human supersoldier unwittingly summoned by the young elf maiden Elenore Redwing. Thrown into a fantasy world of magic, elves, and beast-men, Lambda copes by following his programming, which means following orders and utilizing military force to handle his problems. Meanwhile, Elenore quickly realizes that Lambda is a human war machine whose self-proclaimed mission is to "protect and follow her orders," and must quickly figure out how to deal with a being whose sole purpose is to fight. Follow the adventures of the least-likely familiar and his elven commander as they make friends, battle monsters, and perhaps save the world.