When we first meet Tjaden, he is in ecstasy over the excess food rations made available by the death of so many soldiers. The guy eats like a horse. Tjaden is a peer of protagonist Paul and is portrayed as someone who tries to drink in all of life's pleasures. For all that eating, he's skinny. His gig back home is that of a locksmith. Maybe there's heavy symbolism there – what is he unlocking? Or maybe he is the naïve Adam (of Eve fame) who God put on this earth to just eat, drink, and enjoy rather than ask a lot of deep questions of the Garden.
OK, so he's not a deep thinker. Tjaden has a uniquely strong defiant streak against authority and he clashes regularly with commandant Himmelstoss. Why? Well, Tjaden is a bed-wetter. Himmelstoss blames this on "laziness," but most likely, Tjaden can't help it. Tjaden is humiliated by being placed in the top bunk in basic training by Himmelstoss to drip on the poor guy below him (who's another bed-wetter). And then they reverse. Having received such treatment, it's no wonder that Tjaden is stoked when Himmelstoss is sent to the Front with them. The rules at the Front are different, and rank and military hierarchies count for a lot less in the face of speeding bullets. When Paul's friend ambush Himmelstoss on his way home from a pub, we sense a mildly homo-erotic tone in the way that Tjaden unbuttons and yanks down Himmelstoss's pants so he can be whipped. Later, Tjaden tells Paul that the "thrashing was the high-water mark of his life" (5.5) and that he often dreams of it.
In Chapter Five, when Himmelstoss accosts the group sitting in a field, Tjaden doesn't stand or salute. Tjaden tells Himmelstoss he's a dirty hound (we guess that was a bad thing in the early 1900s), and, when Himmelstoss asks for a sign of respect, Tjaden, sitting, tilts left and farts. Upwind. Threatened with a court-martial, Tjaden doesn't care. But he does hide. The other guys feign ignorance of his whereabouts and Himmelstoss is frustrated.
But he is eventually caught and court-martialed. At the field tribunal, Tjaden tells of the bed-wetting thing and Himmelstoss's abuses. The judge, one of the few rational authority figures in the book, gives a much-reduced sentence and a wrist-slap to Himmelstoss: "He understands it all right though, and lectures, Himmelstoss, making it plain to him that the front isn't a parade-ground" (5.149).
Comfort food continually drives Tjaden's mood throughout. In fact, it is his offering of army bread across the river to the French women that allows them to cross the river and get a bit of lovin'. Tjaden's death comes after long battle marches, when he and his comrades are emaciated, gray, listless, and lifeless. Food is life for Tjaden. When it is scarce, he loses his strength and power.