In writing a character analysis, there are many ways to open an analysis. One way of an opening sentence would be to discuss how the character plays a large impact in the work. Since the character analysis is going to center on the central figure and their dimensions throughout the work, opening your analysis with something that states this might be a good start. Another starting sentence could be to explain how important the particular character is in the work. This might lend itself to plot summarizing as well as might hold the potential to guide you off course, if not careful, but this might be a good start in that the analysis establishes the importance of the character in the work and provides the justification behind the character analysis.