Helena is a brilliant neuroscientist who, at the beginning of the novel, considers it her life calling to find a way to capture memories for people with Alzheimer’s. Helena’s mother suffers from Alzheimer’s, making this work very personal. As a result, Helena is a workaholic who jumps at the chance to increase her funding and begin human trials. Helena also has a strong moral compass: she insists that she should be the first subject of human testing, and when she realizes how dangerous her invention is, she becomes firmly opposed to its use.

Although it’s painful for Helena, she accepts that the chair will never help her mother. Within a few years of escaping from the oil rig, Helena determines that she is willing to die to destroy the chair and to erase the multiple timelines. Eventually, she does just this, using the chair so heavily in her attempts to stop its invention that she loses all sense of herself and dies. By living multiple lives, Helena amasses a huge amount of scientific expertise and becomes self-assured and determined. In the Epilogue, when Barry sees her again, she is back to her first self: principled, consumed with work, messy, passionate, and a little distracted.