Symbolism, Imagery, Allegory
Jellicoe Road should probably have some kind of warning label on the cover telling cat lovers to exercise caution when reading this book. After all, it's hard for any animal lover to read the account of Taylor drowning Hannah's cat in the river and not feel a sense of loss. Still, poor Chairman Meow, the five's favorite feline, plays a critical role in the story as a symbol of the continued grief Hannah and Jude feel as survivors.
While Hannah has a relationship with the cat, he isn't officially hers, and Taylor seems kind of glad about that: "I hate the cat and the cat hates me," she tells us. "He's feral, with a tail that always looks like it's been caught in a state of fright" (3.23). Hannah suspects his perpetual state of fear comes from having seen something that "scared the hell out of him a very long time ago" (3.25). The animal is also decrepit, sick, and just waiting for someone to show compassion on him and remove him from his suffering. Unfortunately, though, Hannah doesn't have the guts.
The further we get into her manuscript, the easier it for us to understand why: Chairman Meow was Webb's cat, as well as the "Chairman Meow" named as author of the Little Purple Book. The cat even spends the night with Narnie after she contemplates suicide, "snuggling […] in next to Narnie" (12.109). This makes Hannah's reaction to the cat actually make sense: She doesn't want to take ownership of him because it would be too much of a reminder of the past, but she still shows compassion on him by feeding him.
Ultimately Taylor takes responsibility for the cat's suffering and drowns him in the river by Hannah's house. In a way, this complicates things as far as the cat's symbolic significance goes. Because the cat is sitting in the tree with Webb during the epilogue, it's probably a good guess that he witnessed Webb's death and has been gradually dying ever since. The loss has been as much of a cause of suffering for him as it's been for Hannah, and just as the cat needs Taylor to relieve him of it, the survivors of Jellicoe Road need to let go as well.