Doc came down from the Class to live in Lux and research Texhnolyze. She despises the people of the Class and doesn't really care for the people of Lux, either. She simply wants to create the best Texhnolyze out there - one that will completely fuse with a human.
While in Lux, she treats both Oonishi and Ichise. She uses Ichise as sort of a guinea pig at first, but kind of falls in love with him as time goes on. I guess the phrase 'married to your work' could be used in this situation. Eventually she finishes her research, but when she goes to present it to Kanno, he rejects her and attempts to kill her. He then uses her research to create the Shapes instead of putting it to use the way she wanted it to be used: to create humans who could realize a greater potential. Afterwards, she falls into a downward spiral of self-pity and drinks her life away. Ichise eventually comes back to retrieve her and get her to help heal the men who were wounded in fights against Shapes. She continues to bitch on the way back to Lux that it's pointless to fight against them. She forces Ichise to hold her tigh and then tells him that they should run away to Gabe and find a place to live. They run into Oonishi and Shinji who ask her to go to the upper world to warn people about Kanno's plans. She agrees to go and warn the Class. Upon arriving, she realizes that everyone there has already given up on survival and all her work on Texhnolyze as an evolutionary trigger for the human species was in vain. She tried to warn Saginuma about Kanno's plans, but he doesn't seem to care all that much or even consider them a threat. Afterwards, she falls back into her depression and decides to stay behind since she has nothing left to live for. We are led to believe she drowned herself after Ichise left. She returns as a shadow in the final episode and activates the final amount of power left in Ichise's Texhnolyze, which enables him to beat the men who killed Oonishi.(Source: somehow-somday.com)