I am writing a paper for my history degree. My thesis is about how you cannot stereotype all individual soldiers to treat their POW's the same way in WWII. I have found plenty of examples of Japanese, Italian and German soldiers being friendly to their captives. But I cannot seem to find any sources of US or British soldiers being mean to their captives. POW's in Allied hands seemed to have it pretty nice compared to POW's in Axis' hands. So to help break the stereotype I need to find a source of US or British soldier(s) breaking the norm and not treating their POW's poorly or not as good. Thanks.
I would like to turn your question on its head, actually. If you are having trouble finding examples of Allied soldiers mistreating captives, while the records are full of descriptions of Axis abuse of POWs, perhaps we should take a minute to think about why that might be rather than continue to search for a mold-breaking example here or there.
You are correct that there are plenty of individual examples of a kind-hearted Wehrmacht soldier or the like, just as there are, yes, individual examples of Allied abuses (the alleged retaliatory killings of SS prisoners at Chenogne, for instance.) But you don't see the same widespread discussion of Allied war crimes as you see of Axis war crimes because at a systemic level the Western Allies did not engage in criminal behavior the way the Axis armies did. The kindly Wehrmacht soldier was, no matter how many kittens he was photographed with and no matter how many sweet letters he wrote to his children, a member of an entirely criminal organization. I would refer you to this FAQ answer by /u/commiespaceinvader discussing how thoroughly dirty the Wehrmacht was. Omer Bartov's Hitler's Army: Soldiers, Nazis, and War in the Third Reich, Christopher Browning's Ordinary Men: Reserve Police Battalion 101 and the Final Solution in Poland, and Richard Evans' The Third Reich at War are really indispensable works on understanding the why and how of criminal behavior in the Wehrmacht.
To be rather blunt, your thesis is problematic at a very basic level. By highlighting token examples of friendly Germans and cruel Americans & Brits, you're implying a level of moral equivalency that just isn't there. Both sides are emphatically not the same here, and the narrative you pose here only serves to obscure the reality of the German military's behavior.
With that said, I have not discussed anything in the Pacific theater, because I don't know very much about it. My understanding is that the Pacific was a dirtier war, largely owing to racism on the part of American troops and the general Japanese disdain for surrender; I would not be surprised if you found more evidence of Allied POW abuse here. You didn't ask about the Soviets, but it would be remiss of me not to mention them. They did not kill POWs to the same extent that the Wehrmacht did, but it did happen, and the conditions in Soviet POW camps were certainly appalling.