I've completed TWD a few times now, attempting to give Lee/Clem different personalities each playthrough. Over time I've noticed that there are some choices and dialogue options that I can't bring myself to use, no matter how much of an jerkass my character is. Here are some examples...
Siding with Larry at the drugstore
Making Kenny kill Duck
Hiding the bite
Lying to Walt
Are there any lines that you refuse to cross? Any options that are just too brutal, cowardly or mean?