I consider Iron Bars to be one of the great characters of MT. In typical SE fashion, he comes out of absolute nowhere, almost 2/3 of the way thru the book, as a supporting character in Seren's storyline, and proceeds to kill Rhulad in passing, bring justice on a bunch of bandits, save Seren three or four times, take out the Pack with some help but then rock the whole Tarthenal Gods bit. "Look... He's smiling." remains one of my favourite lines in the Malazan books, right after "Fucking dragon." in RG
It has been noted that, while many of us liked the IB storyline in RCG, especially the Seguleh confrontation, the plotline stayed entirely separate from the rest of the story. every other plotline met up in the big finishes except IB & co, who spent the book trying to get there, missed the show and ended up chained and en route to the Stormwall.
And the doubters among you cried 'Why? Why ICE?!? Why did you cheat us so???" well, i have faith...

On the reread in MT... during the fight with the Serenghal (the five Tarthenal gods), Corlo is running Mokra interference for Iron Bars... and during Corlo's inner monologue (mmpb, p591 thank you amazon search inside function):
I think his plan runs across multiple books.
And i think IB is the Avowed who is going to take Skinner down (or give it a damn good shot) somewhere further along the way.
- Abyss, smiling.