M. Gillenormand is Marius's maternal grandfather. He is generally well-liked, "quick-witted," and lively, and maintains a high opinion of himself. At nearly ninety years old, Gillenormand is still "full of life" and often attracts interest from his neighbors. However, Gillenormand's "suffering expressed itself in rage," and he is prone to anger and aggression.
Hugo comments that Gillenormand belongs to another age. He represents the outdated era against which young people like Enjolras actively rebel, striving to rid modern France of its lingering influence. Gillenormand embodies the complete antithesis of the values upheld by Colonel Georges Pontmercy, as well as the Friends of the ABC. A staunch monarchist, he abhors Napoleon and the idea of the Republic, holds "the year 1789 in horror," and reduces the French Revolution to "a load of scoundrels." Consequently, he considers Pontmercy "a disgrace to the family" and cuts off all connection between him and Marius.
Gillenormand's influence on Marius is perhaps his most prominent role in the novel. Domineering and stubborn, he shapes Marius's views of politics and his father early on. It is not until Marius begins to seek his own understanding of the world and his father that he becomes a Republican and begins to idolize Napoleon and Pontmercy. This prompts Marius to sever all ties with his grandfather.
Though a complicated character, Gillenormand is ultimately redeemable due to his deep love for his grandson. After Marius is severely injured in the June Rebellion, Gillenormand is distraught and eventually comes to accept Marius for who he is. The two reconcile, and he gives Marius his blessing to marry Cosette and even pretends to agree with Marius's politics, remarking that "there was nothing evil about those great men of the Revolution." His willingness to place Marius above petty rivalries and long-held, though outdated, beliefs reflects larger themes about the profound, transformative power of love.