Chaplain Titan-Brother Humongus or the Warprunners
Some of the most ancient and reverred Titans in existance, once, all Titan orders had their own Chaplian Titan but now only a few battle-scarred behemoths remain. Only deployed where there is a deep seated heretic or chaotic influence and the will of the Emperor must be imposed to insure victory on the battlefield. Because of their high moral and spiritual value (it is said that each Chaplian Titan containes the pure essence and blood of the Emporer) they are very rarely seen without at the very least a Warlord and Reaver escort
Brother Humongus is Garrisoned by Bishop Ralph of the Ginger order and Brother Barry, they have spread the word and imposed the will of the Emporer throughout many worlds and systems along with distibuting countless gallons of Tea and many tons of custard creams
OK, purely fictional fiction on my behalf but hey, every unit needs its own spiritual input and a 100 foot vicar sporting a power glove and plasma blaster has to fill you with a little faith, surely!
Initially scratched my head wondering how I was going to approach the painting. As it happens just dived in one afternoon and decided to make it look like a Marine Chaplain, after all he is a Chaplain Titan!