Born on Fredas 18th of Sun's Height in the 3th era, in a khajiit camp near Dawnstar in the region of Himmelsrand, he was the bastard son of the father Do'isco and mother Ko'zra the Mage. Shortly after his birth Do'isco and Ko'zra married and moved carefree to Riften due to his mother's friendship with the Jarl.
When he was a cub, M'ërbert was trained and educated by his father in the art of battle with short blades and bows. And due to his khajiit blood and agility, stealth was already embedded in him.
When he was 8 years old his mother gave birth to his sister, Ma'reka. His sister and him grew loving each other deeply and they would always play together. Ma'reka admired him and wished to make him proud of her, and because of that she mistakenly stole a couple of septims from an argonian woman monthly, witch without her knowing was apart of The Dark Brotherhood, after a couple of mouths when the argonian woman found that some of her money was missing got angry and started searching for the thief.
While growing up he met a Dunmer boy that was about the same age as he was, named Andris. Both became best friends quickly and often made pranks around the town. At the age of 16 he killed his first victim, the very same argonian woman from the Dark Brotherhood, after she found that his sister was stealing money from her and tried to kidnap and sell her as a slave. Luckily for him the argonian woman was only an apprentice and owed money to The Dark Brotherhood and so the Brotherhood didn't care so much about M'ërbert. After that both of them decided to keep the event a secret from their parents. In the following weeks after the event, he started training harder with his best friend. Even if he was training all day M'ërbert still got time to play with his sister and his friends, he was cheerful all the time, even if his days were full of training.
Two years after the incident with the argonian woman, The Brotherhood remembered that the she owed them money so they sent their new apprentice, a wood elf girl Rizza, to kill him and demonstrate her skills and power. While she stalked him trying to gather information Rizza found out that he was honorable and kind. After she saw that he was helping other people, even if the task was too much for him, she saw him help a lost little high elf girl get back to her family after she wondered away from them, when the high elf's parents wanted to repay him with a bag of septims, but he refused and said that all he wanted in return was to see the girl again and that she met his sister. After stalking him for one week and witnessing all his deeds she attacked him on a sunny Tridas after he finished training and tried to take advantage thinking he will be tired and weakened from training all day. But when she attacked him he was ready because he knew of her presence from the start. And in the time that she was staking him he grew fond of her and didn't attack her back nor he defended himself.
While fighting M'ërbert fell to the ground from all the wounds that Rizza gave him during the attack. When he fell down she expected him to plea for his life but, he did not beg for his life but he begged for the safety of his little sister, that was home sleeping while his mother and father were away with a khajiit caravan that was going to Whiterun. When Rizza heard that he's begging for his sisters safety and not for his own life she couldn't bring herself to kill him. So she helped M'ërbert get up and after that, treated his wounds and told him that she hopes to meet him again. After Rizza left he went inside the house only to find that his sister was still sleeping like a giant, clueless of what just happen, he covered her with a blanket and went to sleep too.