As you look at him you can see a tall and stout man of Rohan who has grey eyes with piercing gaze and a light beard.

Usually he behaves judiciously and his voice is calm. He's in his mid-twenties. Since his childhood there is a small vertical scar next to his right eyebrow. 
He always carries two swords: a graceful one-handed longsword in a black sheath on his left and a somewhat shorter sword on his right side, hanging from the weapon belt. On his neck rests a simple leather strap necklace, holding a small hammer shaped pendant which is adorned with runes.

Following the tradition of his forefathers, he used to be a guard in the Border Watch of Stonedeans. He had to leave his homeland with a guard unit by the command of Thurferth. According to their task they've scouted the settlements and strategical movements of dúnlanders. Their way led to Breeland where he found allies and thus successfully completed the tasks he's been given.

After he travelled back to Rohan he settled down in Aldburg temporarily. He has been trying to find his fellow riders of the Eored he travelled with.
In the meantime he had to make a living somehow. 
So for a while he has been selling his combat skills and slayed orcs or any creature that threatens the lives of the people. Thus he has gained remarkable knowledge on various beasts. He he favors the bow for hunting and in mounted combat.

Originally his plan was to return to his family in Woodhurst for he misses his beloved little sister badly.
But upon arriving to the town he found out they've left their home and travelled to Edoras, seeking shelter against the revenge of the treacherous Thurferth. Ysmired refused to obey the corrupted guard captain and finally left the Border Watch. He has secretly helped Thane Herubrand and his remaining loyal men to retake the throne.

In the King's City he learned the shocking news from his mother.
Yrnhelm, his father has been imprisoned by Grima because he warned the king about Herubrand's coup over Woodhurst. Grethwen managed to escape from Edoras so she has set out to find her brother and to get help from him.

Ysmired, being unable to gain Theoden's mercy for Yrnhelm, recklessly scouts the countryside trying to find his sister.