Background (in character)
Sparky Bolt earned his cutie mark by being fascinated by machines from an early age. As a colt, he made himself at first a nuisance, then a help, to Mash Tun, the then head engineer at the Sweetwater Brewery. The crucial point was his invention of a more efficient bottle-checking system which finally made his cutie mark appear, and also led to formally becoming Mash Tun's apprentice.
Life went on and Sparky continued to innovate and improve the brewery's systems, leading to increases in quality, production - and profits!
The Transformation of Sparky Bolt
Sparky's life took a somber turn about a year ago when he was summoned to his mother's bedside in Ponyville, where she had retired to live out her old age 'in the light of Harmony'. Sadly, it turned out to be a death watch, and affected the unicorn strongly.
Shortly after the funeral ceremony, Sparky was overcome by the need to flee, and unthinkingly took the shortest route home - through the Everfree Forest.
At some point, Sparky came to his senses just before he was attacked, apparently by wolves. While he was able to kick enough lupine skull to drive them off, he was still mortally wounded. In his words, "And dat vas vhen Hy ztood on my own gutz. Take my advize. Don't ztand on hyour own gutz."
Unknown to him, the fight had attracted the attention of a scouting party of Jägermonsters exploring a portal, apparently created by one of Baron Wulfenbach's experiments. Discovering the battlesite, and the barely alive 'konstruct' (as they naturally assumed Sparky was), the decision was made to offer the 'braff liddle horsie' the Jägerbräu - not only to try and save him, but curry favour with the Spark who constructed him!
The bräu was successful, with a few physiological changes. For one, Sparky's hide changed colour from roan to a deep green, and his teeth became noticably pointed. However, his accent is much lighter than the typical Jäger's.
Details of what happened next and how Sparky got out of the Everfree are scant, and Sparky himself either changes the subject, or, in the case of a persistent questioner, smiles at them. "Being beamed at by a vine zet of fangz zeems to make poniez vanish for zome reazon."
Second Life information
Sparky Bolt is the ponysona of Maku Ibn-Selat.
The base avatar is an Equestria's Pride, customised with a hat, modified red jacket made by Curly Fride, and mane and tail from the I Pity the Foal modkit.
The hat and upper teeth are (heavily modified) prizes from The Jägerbräu Hunt, which took place in 2011. Hunters who found the various waypoints were rewarded with various costumes, skins and avatar parts, including prim teeth.
Future modifications are intended to include skins showing his remaining scars from the battle, and possibly a revamped jacket (which he uses to conceal the worst ones.)