Jim was a fantastic character that was sadly taken from us after walkers hit the Atlanta campsite, and the bulk of the protection was still out on a run looking for guns. He was somehow bitten on his stomach, despite holding his own in the attack and taking out the walker that bit Amy, and it was discovered by Jacqui the next morning that he was infected. The character had seen terrible things, namely his family getting torn apart by the dead, allowing him to escape. He encouraged Lori to keep Carl safe and never let him out of her sight (I’m sure he rolled over in his grave in Season Two). It was genuine concern, and it went a long way. Jim opted to be left at the side of the road rather than accompany the group to the CDC, a journey that would prove almost helpless, despite informing the group with some information about the outbreak and, as revealed much later, that everybody is infected, and that unless your brain is destroyed, you will turn when you die.