He was born to Serathios and Estelle Arclaud, two immortals who loved each other enough that they determined a way for immortals to reproduce. Using the Genisys process, it was possible for two immortals to conceive human children. The children that were born were genetic archetypes for humans, possessing abilities surpassing most humans. They were especially magically talented, as is demonstrated by Serrellious and Hadrien Zephyr, both born to Serathios and Estelle.
Serrellious was intuitively able to manifest his abilities by summoning living creatures and nonliving objects consciously and subconsciously, reforming solid matter.
His twin, Hadrien, was naturally able to bring form to the environment through control of fluids such as water and air. While Hadrien could reform aspects of the water and other fluids around him from a distance, including giving rise to great potential and thermal differences, he lacked the ability to intuitively summon complete items.
On the other hand, Serrellious with his ability to reform solid matter was a master of metal, able to forge the keenest swords and the most durable shields and armors. Eventually, Serrellious was able to imbue seemingly magical properties into his items, granting him similar abilities to Hadrien.
Eventually, Serrellious and Hadrien meet, and Serrellious crafts a hilt imbued with Hadrien’s magic, resulting in the blade known as Lux Tenebris (“Light from Darkness”). Eventually, Hadrien merges into Lux Tenebris to empower it and create Crisaegrim, a Soulblade. Crisaegrim enhances its wielder’s abilities to manipulate fluids at range like Hadrien. When Serrellious wields it, he gains abilities comparable to Hadrien.
Serrellious has similar-scale abilities to Hadrien at close range over all the elements. Simliarly, Hadrien realizes he has the ability to reform solid matter on touch. Serrellious is eventually able to make, for example, enormous potential differences between various regions of his own body (such as his fists) and to generate tremendous controlled current arcs through the air. Hadrien is able to do this at a range, and is not limited to generating such potential hotspots merely on his body.
Consequently, Serrellious is in a sense almost as offensively powerful as Hadrien. However, in sheer destructive ability, Hadrien is foremost.