could I make a comparative study between les mésirables and oliver twist? I think that we can compare many aspects between the two novels such as children, poverty, injustices,,,.
These stories would be great for a comparison study. You might also want to look at the differences and similarities between the two societies. The stories take place in different countries but there are some remarkable similarities between the two cultures. It might also be interesting to compare the effect that each society has on its main characters.
Obviously these two novels speak very explicitly to the themes you mention. Another way to compare the two novels might be in terms of style. Both authors sought to depict the conditions faced by urban people in gritty detail, which is one of the reasons these works are so significant. So you could examine their importance in light of an emerging tradition of literary realism, and compare the ways in which they contributed to this tradition.