From the day he was born the only words used to describe him, was "big" and "violent". then you got two choices, Deal with it or make it more true.
Rickman did the last, when he ended up at a practice play for the Rats nest. He was only there as a spectator, but when the opposing team had cruched the third of the defenceless Linemen, he had enough.
He jumped on the field, with no armour, and started to beat up the opposin teams catcher, a young dwarf. After his frenzy, all that was left of the catcher, was the arm Rickman ripped off him, and beat him with repeatedly.

The Coach saw "some potential" in the young Rat Ogre, and signed him for one season.

Picture a kid, who doesnt need sleep, have uncontestet lunacy and have a mouthful of razorsharp teeth, then you get a pretty good idea on how Una is.
She also have quite the homicidal streak, and usually uses her incredible stupidity to lull the opponent into a false sense of security. Then she scores a Td.

All that being said, Una is a Critter you cant get around. She´ll kill you if you try.