Sesi was conceived and born in the Northern Water Tribe by two non-benders named Corazon and Siku. As their only child, Sesi was treated spoiled and affectionately, which gave rise to quite the demanding personality. As a toddler, Sesi was renowned for being a nagging boy, always desiring attention and entertainment. This was unfortunate for the inexperienced couple, who would constantly have to meet up to his demands to cease his impulses, much to chagrin of his water-bending grandfather Onartok.
Unlike his son and daughter-in-law, Onartok experienced no discomfort when scolding the boy, even when his methods of using water-bending to quell his disrespect was sometimes unecessary. Much to the indignation of Siku, Corazon often had no say when it came to Sesi's punishments, for his father had no shame when it came to penalizing his son as well. Sesi despised Onartok, and Corazon to an extent, because of this. Whenever Onartok came to visit, Sesi would make a mad dash toward Siku, and complain loudly to her.
When Sesi was seven and making yet another fuss, Onartok attempted to strike him with a weak, but forceful water whip. Sesi, noticing the incoming whip inching closer toward him, closed his eyes and swat the air with his hand. Once he opened his eyes, he was welcomed to the sight of his family's astonishment. Bewildered, Sesi opened his mouth to speak, until he noticed the puddle of water around his feet. He had stopped the water whip from coming at him. He was a water-bender.
Siku and Corazon were pleased upon this revelation, but Onartok even more so. A mad grin was etched on his face as he requested that the boy stay with him under his tutelage. Siku was absolutely irate, but after a bit of counseling from Corazon, she begrudgingly agreed this was the proper take of action to handle the situation. During his prime, Onartok was a proud water-bender, though now reduced to a former shell of what he used to be his old age. However, much of his knowledge endured, knowledge that could be passed down to the next generation.
Against Sesi's wishes, he was taken from his beloved home, and was brought to Onartok's domain. Training began almost immediately. Sesi hated every second of it. As his grandfather would drone on and on about the techniques of water-bending, he'd doze off and disregard his teachings, prompting Onartok to often give him a vicious smack to the forehead. He'd visit his parents on occasion, though a considerable amount of his time was spent with Onartok.
Onartok molded his previously inconsiderate grandson into a sharp, disciplined young man. As each day passed, Malik learned to respect others, as well as his gift. He used it responsibly and wouldn't dare to intentionally attack someone, though that was partly due to his deferential fear of his grandfather.
Six years passed and Onartok had grown ill with a perennial disease. With his age and ailing health, the healers knew and told Sesi it was only a matter of time until he naturally succumbed and yielded to the sickness. Sesi was somber. Though he had initially disliked Onartok, he had raised him to become such a refined individual. Seeing him coughing and wheezing in bed just seemed impossible.
Shortly after the news came to pass, Sesi moved back with his parents, with Onartok accompanying him. The trio worked to stabilize Onartok's condition and ensure he would last longer than predicted, but alas, he passed several months later.
Sesi was morose, but continued to persist, as Onartok would've wanted him to. He practiced everyday, striving to assure that his grandfather's teaching would not go to waste. A year after Onartok's death, his younger brother Nilak was born. While his parents were away, Sesi would tend to the child, and felt a close bond when by him.
Sesi wasn't that close with most of the kids of the tribe, and preferred to move on his own. However, he did have a good relationship with a boy his age named Karpok, and the two enjoyed adventuring the land when they had the time. Karpok wanted to explore the world and have Sesi at his side. Sesi, though reluctant, would eventually help him achieve this dream.
The two were 18 when they first set off on their own. With a few yuans to spare, they boarded a boat and began their journey. Most of the time they barely got by, though they managed somehow. Once at the Earth Republic, however, Sesi learned that Karpok wanted to establish a little shop with a sweetheart he encountered. Sesi found this incredulous, and attempted to barter him out of it, but Karpok refused to relent. Reluctantly, Sesi said his farewells and left the Earth Republic by himself.
He decided it time to head back home, though he ended up changing route and went to the Southern Wastes instead. He was curious. At the Northern Water Tribe, he's always heard stories of the South, stories claiming the place was bustling with pirates and thieves. Upon arrival, he was surprised by the horrid conditions, as his knowledge of the Wastes wasn't entirely keen. Disgusted, he was ready to head back when he bumped into a miss called Sura.
He found her beauty enchanting, even when it was besmirched by the ugliness of her dwellings. He begged her to come with him, and though she hesitant at first, she eventually fell for the water-bender. With Sura by his side, Sesi forsook all negativity, and was happy to announce to his parents he found the one once he arrived back.
Most of the members of the tribe despised her due to her circumstances, but those who grew to know her admired her willingness to get things done. Corazon and Siku was just happy their son was back and merry, while Nilak loved his new "older sister."
A year and a half passed and Sura was pregnant with Sesi's child. But during the delivery, something tragic occurred. Sura was unable to survive her parturition, while the child was a stillbirth. This left Sesi broken and continued to affect him to this day.
Every day he'd catch a sympathetic stare, but he ignored their sympathy. He became a shut-in and shoved everyone out of his life. He was constantly on his own, having nothing to soothe his grief.
A year later, he would start to crawl out of this. Unexpectedly, it was Nilak who became his catalyst. No longer unable to withstand his brother's dejection, he slapped him with a powerful water whip, reminiscent of Sesi's times with Onartok. Sesi was surprised, having never known Nilak was a water-bender, though this mainly because he was either away or too deep in his own misgivings for Nilak to show him.
He apologized to his family for the way he has been, but they all accepted him with open arms. He then apologized for no longer having the heart to stay within the tribe, but they all seemed unsurprised. Even Siku knew it was only a matter of time until her cub left the den for good.
Corazon told him about the Citizenship Project within Republic City, and that if he ever wants to start a new beginning, it'd be best to start there. So at the age of 21, Sesi set foot on the foundation on the city, and has been there ever since.