I remembered reading a play-by-post roleplaying forum where a person created a dwarf who rode cows into battle.
...and my google-fu gets results! Pretty good writing actually.
It is a lesson drilled into most dwarves at an early age- Find what you want to do, and do nothing but it. Like the mountains you grew up in, be unmovable in your expertise, and listen to nobody who tells you any different. A dwarven promise should be as reliable as a masterfully forged sword.
Unfortunately, whoever decided upon these traditions didn't account for Rapps. Most of his clan trained as miners, smelters, blacksmiths, mechanics, surveyors, and a whole variety of professions centered around metal and rocks. They did this because their parents had, and dwarven tradition does not break.
Rapps, however, was a Cattlesmasher. He was born from a long line of Cattlesmashers, apparently descended from Lars Cattlesmasher, who apparently took too many bumps to his head whilst mining and decided to train battlecows. But, like a true dwarf, he set his mind, soul, and life to it, and his family followed.
And Rapps couldn't have been happier. Strange how borderline insanity is hereditary.
He mulled over this as he sat on Daisy's back, in the cool, dark room in front of his entrance to the Colloseum. His grandpappy would have been so proud. He smiled, a joyful tear rolling into his beard.
Drums echoed as the door in front of him was hoisted upwards. The light spilled into the room, revealing a combatant very different from before. Gone was the rusted steel armour around Daisy, the cow instead being covered in gleaming dwarven plate, hardened to the strength of a diamond and polished to a mirror sheen. The axe was no longer an ill-maintained weapon of bludgeoning, instead being sharpened by a small army of dwarven blacksmiths, all travelling far from home to see Rapps. It glinted as the light fell across it, the edge razor-sharp, the handle having been replaced with old, hardy stonewood, the haft re-balanced to suit the dwarves exact lumpy proportions.
He looked away from his beautiful new weapon, and down to his companion. She was silent. And calm. Rapps leant down, closer to her ear.
' 'ee alright, girl? '
The steed offered no reply, but began pacing slowly towards the gate, not faltering, standing at her full, fearsome height. It was a thing to behold for Rapps, who would hold this moment of peace in his mind until the day he died.
And then the cheering began.
A rush of sound filled the arena, cheers rising from the crowd as the gate was opened. The noise was nearly unbearable, but Daisy remained still. She was no longer being controlled by her own instincts, but by her master. Wheras many riders try to break the will of their mounts in order to allow them to be ridden, Rapps had dedicated ten years to not breaking Daisy's will, but bonding it with his own. And she had finally done so. A sniffle came from behind the thick beard.
'Ah, you would choose now, wouldn't ye, yah stupid cow!' he said, wiping his nose on his chainmailed arm. Pulling himself together, he looked ahead, and was about to rile Daisy to go, when she took off by herself, charging into the arena.
The cheers redoubled as Rapps and Daisy exploded from their gate, galloping across the ground, each hoofbeat a war drum for an army of two. They charged forwards as one, Rapps leaning forwards against the cow, his beard and hair forced back in a wild, messy slipstream. Rapps scanned the crowd, his eyes closing in on a tiny portion thanks to the sun glaring off their helmets. The dwarven crowd.
Daisy turned with no instruction, slowing as she neared the crowd, who seemed to have already consumed enough alcohol per head to knock out five elephants. He roared up at them, over the crowd.
' Oi! OI! Where the 'ecks Grol Moneyfist? '
A small, yet well-dressed dwarf stood up and yelled something at Rapps, pointing at himself. Rapps replied.
' Right! What are the odds on the short bloke with the body odour and the cow? '
The dwarf in the crowd held up one short, podgy finger on one hand, and five on the other. 1:5.
' One to bloody five? Right then! Get me sixteen 'undred on him! '
The fat dwarf laughed, his joy inaudible over the drunken crowd. Rapps threw them a cheer, raising his axe as he did. Showmanship was a new feature in his family, and it was here to stay. He reached down, pulling his helmet from the edge of the saddle, and dropping it over his head. Wheras his axe had been reforged, his armour replaced, his steed re-hooved, his helmet was still rusted and old. He would have liked to say that it was his great-grandfathers, and often lied to say it did (dwarven women love heirlooms), but in all truth, it had been forged from Daisy's first set of shoes. The old, nearly rusted iron was ill-fitting and obviously weak, but he would have had nothing different.
Crowd-pleasing over, he coaxed Daisy forwards, scanning the arena for his opponent.