Appearance and Personality
It's always nigh on impossible to distinguish between individual Haruchai. Clyme is again of average height with typical sinewy build. Just like his brethren, he has dark wavy hair and is yet another fan of the traditional Haruchai earth-coloured tunic. However, unusually Clyme is one of the three members of the Humbled (nb: this is not a boy band) and as such has voluntarily had two fingers chopped off his right hand - doesn't sound much like a club I'd like to join, no matter how exclusive.
When it comes to personality, Clyme's got all the typical Haruchai personality traits - stoic and impassive, utterly convinced of his own absolute moral rectitude, unswervingly steadfast and overweeningly courageous. With that collection of characteristics, one can only fear the worst for the guy - in one of SRD's universes, he's got "sacrifice" written all over him.
Role within the Third Chronicles
Clyme, like the other two members of the Humbled, decides that he should stick to Covenant's side like glue (in fact, like a clam, rather than a Clyme) as soon as he has clapped eyes on him. He thus volunteers himself as one of the ur-Lord's permanent bodyguards.
After the usual series of horrendous trials in which it's difficult to tell the various Humbled apart amid the whirling, kicking and flying body parts, Clyme comes into his own after he, Branl and Covenant meet his all-time hero, ak-haru Brinn of the Haruchai, who, what with the rousing of Wormy has recently been made redundant from his job as Guardian of the One Tree. Running into his posterboy idol must come as a bit of a shock to Clyme, since, after spending a good few pages taking the mickey out of all present-day Haruchais as a whole, Brinn informs the trio that turiya raver is about to possess the Lurker. Needless to say, this would be a Very Bad Thing™.
So off the little group go, into the Sarangrave Flat to see if they can save the outsized squiddly diddly from possession. This they succeed in doing, but only by Clyme in an act of suicidal bravery choosing to let the raver possess him instead, then grimly containing it within himself while he exhorts his kinsman Brinn to finely dice him into meaty chunks with the krill. This Brinn duly does with customary Haruchai weapons expertise and efficiency, turning both Clyme and simultaneously the raver he has imprisoned internally into a gory cole slaw, and thus ending the existence of both.
This internalization of ravers and then allowing oneself to be smooshed or sliced out of existence seems to be the most effective way of dealing with the malign spirits once and for all - viz. the example of Grimmand Honninscrave.